05 Feb 2024
04:30 PM

Observation of fractional quantum anomalous Hall effect

Prof. Xiaodong Xu (University of Washington)

The interplay between spontaneous symmetry breaking and topology can result in exotic quantum states of matter. A celebrated example is the quantum anomalous Hall (QAH) effect, which exhibits an integer quantum Hall effect at zero magnetic field due to topologically nontrivial bands and intrinsic magnetism. In the presence of strong electron-electron interactions, fractional-QAH (FQAH) effect at zero magnetic field can emerge, which is a lattice analog of fractional quantum Hall effect without Landau level formation. In this talk, I will present experimental observation of FQAH effect in twisted MoTe2 bilayer, using combined magneto-optical and -transport measurements. In addition, we find an anomalous Hall state near the filling factor -1/2, whose behavior resembles that of the composite Fermi liquid phase in the half-filled lowest Landau level of a two-dimensional electron gas at high magnetic field. Direct observation of the FQAH and associated effects paves the way for researching charge fractionalization and anyonic statistics at zero magnetic field.

Seminarroom 1+2+3
08 Apr 2024
04:30 PM

Gutzwiller Colloquium - Moiré is different: New Twists in the Tale of Strong Correlations

Prof. Siddharth Parameswaran (University of Oxford)

I will give an overview of how advances in engineering twisted two-dimensional materials with a “moiré superlattice” have revealed a rich playground for investigations into strongly-correlated electronic matter. I’ll introduce the theories deployed to explain some of the experimental puzzles that arise and give a personal view on the most promising lines of future work. Along the way, I will illustrate how some of these ideas echo historic themes in condensed matter physics, including Martin Gutzwiller’s visionary ideas on the many-body problem, and mention how they tie in to past and future activities at MPI-PKS.

Seminarroom 1+2+3
15 Apr 2024
04:30 PM

Nonequilibrium statistical physics in living systems: The role of energy dissipation for biological functions

Dr. Yuhai Tu (IBM T. J. Watson Research Center)

Living systems from biochemical networks to neural networks are responsible for carrying out precise biological functions and information processing tasks. However, most of these complex networks operate far out of equilibrium in which equilibrium statistical mechanics fails to describe even their steady state properties. It thus remains a major challenge in biological physics to develop a theoretical framework for studying these highly nonequilibrium complex systems. A central problem in living (or active) systems is how they manage to perform vital functions (e.g., adaptation, replication, and computing, etc.) accurately by using highly noisy signals. What are the mechanisms to control noise for accurate information processing? What are the energy costs for implementing these mechanisms? What are the design principles for achieving these biological functions efficiently? In the past 16 years, we have been working to answer these questions in various biochemical systems including ultra-sensitive switch, sensory adaptation, accurate biochemical oscillations, and collective behaviors (e.g., synchronization, flocking, and pattern formation) by using tools and concepts from nonequilibrium statistical physics. In this talk, we will first describe the general background on the topic followed by presenting some of our work related to the role of energy dissipation for important biological functions for sensory adaptation and (if time permits) synchronization of molecular clocks.

Seminarroom 1+2+3
22 Apr 2024
04:30 PM

Colloquium: Bacterial Biofilms: Navigating the Confluence between Physics and Biology

Prof. Eleonora Secchi (ETH Zurich)

Biofilms are communities of microorganisms that embed themselves in a matrix of self-secreted extracellular polymeric substances. The matrix protects the microbial community from chemical and mechanical insults, thus favoring its survival and evolutionary success. Biofilms are the primary mode of growth of bacteria and have a crucial impact in environmental, industrial, and medical settings. However, there is a significant lack of understanding about how the physical structure and chemical composition of biofilms determine their resistance to harsh environments. Our work focuses on the bio-physical drivers of biofilm assembly and the emergence of distinctive morphological and mechanical properties. I will showcase examples of biofilms grown under different environmental conditions, ranging from moist surfaces to surfaces exposed to fluid flow and porous media and by different bacterial species. For each case, I will present the experimental platform we developed to investigate the specific system and the results we obtained. Through our research, we discovered that the interplay between biological functions and physics mechanisms controls biofilm assembly, morphology, and rheology, ultimately affecting their physiological protective function. Shedding light on this interplay can help us control biofilm development and shows the prominent role that material science can play in developing novel antimicrobial and antifouling strategies.

Seminarroom 1+2+3
13 May 2024
04:30 PM

Medium-mediated control of active colloids

Prof. Ignacio Pagonabarraga (Universitat de Barcelona)

Active colloids use a variety of mechanisms to self-propel. They usually involve an exchange of matter or energy with the medium in which they are suspended. Because of the intrinsic non-equilibrium nature of such coupling, the properties and regimes of self-propulsion are richer and more varied than the ones associated to their underlying equilibrium properties. In this presentation I will analyze the implications that the dynamic coupling between colloids and reactants may have in how colloids self-propel and how such dynamical couplings can be used to control and manipulate the individual and collective motion of colloids.

Seminarroom 1+2+3
27 May 2024
04:30 PM

Colloquium: High order van Hove singularities meet flat bands

Prof. Joseph Betouras (Loughborough University)

Seminarroom 1+2+3
17 Jun 2024
04:30 PM

Colloquium: Lighting up Superconductivity

Prof. Eugene Demler (ETH Zurich)


Seminarroom 1+2+3
24 Jun 2024
04:30 PM


Seminarroom 1+2+3
01 Jul 2024
04:30 PM

Self-organisation of proteins in cells

Prof. Erwin Frey (LMU Munich)

Protein pattern formation is essential for the spatial organisation of intracellular processes like cell division and flagellum positioning. A prominent example of intracellular patterns is the oscillatory pole-to-pole oscillations of Min proteins in E. coli, whose function is to ensure precise cell division. Cell polarisation, a prerequisite for processes such as stem cell differentiation and cell polarity in yeast, is also mediated by a diffusion-reaction process. More generally, these functional modules of cells serve as model systems for self-organisation, one of the core principles of life. Under which conditions spatiotemporal patterns emerge and how biochemical and geometrical factors regulate these patterns are major aspects of current research. In this talk, I will review recent theoretical and experimental advances in the field of intracellular pattern formation, focusing on general design principles and fundamental physical mechanisms.

Seminarroom 1+2+3
08 Jul 2024
04:30 PM

Insulating Magnetic Rare-Earth Pyrochlores: Frustrated Magnets for Every Taste

Prof. Michel Gingras (University of Waterloo)

Seminarroom 1+2+3
15 Jul 2024
04:30 PM

Boundaries, Inclusions, and Disorder in Active Matter

Prof. Mehran Kardar (Massachusetts Institute of Technology)

Active systems are driven out of equilibrium by exchanging energy and momentum with their environment. This endows them with anomalous mechanical properties which leads to rich phenomena when active fluids are in contact with boundaries, inclusions, or disordered potentials. Indeed, studies of the mechanical pressure of active fluids and of the dynamics of passive tracers have shown that active systems impact their environment in non-trivial ways, for example, by propelling and rotating anisotropic inclusions. Conversely, the long-ranged density and current modulations induced by localized obstacles show how the environment can have a far-reaching impact on active fluids. This is best exemplified by the propensity of bulk and boundary disorder to destroy bulk phase separation in active matter, showing active systems to be much more sensitive to their surroundings than passive ones.

Seminarroom 1+2+3
19 Aug 2024
04:30 PM


Seminarroom 1+2+3
09 Sep 2024
04:30 PM

Machine Learning Improves Quantum Technologies

Florian Marquardt (Max Planck Institute for the Science of Light)

Seminarroom 1+2+3
16 Sep 2024
04:30 PM


Prof. David Weld (UC Santa Barbara)


Seminarroom 1+2+3
23 Sep 2024
04:30 PM

Copernicus Revisited: Is the Earth Special?

Prof. Laura Kreidberg (Max Planck Institute for Astronomy)

Nearly 500 years ago, Nicolas Copernicus published his disruptive theory that Earth is not the center of the universe. This "Copernican demotion" has held fast over the centuries, as astronomers have learned that there is nothing particularly remarkable about Earth or even the Milky Way. In the last two decades, however, a new test of the Copernican Principle has emerged -- the discovery of an abundance of planets orbiting other stars. These discoveries allow us to put Earth in context and evaluate whether the formation, architecture, and present-day characteristics of our Solar System are in fact typical. One of the biggest open questions is whether Earth-like exoplanets have water, a key ingredient for life. Thanks to the revolutionary new observing capabilities of the James Webb Space Telescope (JWST), it is possible to characterize the atmospheres of Earth-sized worlds for the first time. In this talk, I will share the latest observations of rocky exoplanet atmospheres from JWST, discuss the implications for their water abundances in comparison to the Earth, and answer the question: was Copernicus wrong?

Seminarroom 1+2+3
28 Oct 2024
04:30 PM


Prof. Thomas Kühne (University of Paderborn)


Seminarroom 1+2+3
30 Jan 2023
04:30 PM

Colloquium: The Multiple Roles of Mechanics in Shaping Organisms

Prof. Otger Campàs (Physics of Life, TU Dresden)

Seminarroom 1+2+3
20 Mar 2023
04:30 PM

Topology in Biology

Prof. Julia Yeomans (University of Oxford)

Active materials such as bacteria, molecular motors and self-propelled colloids are Nature’s engines. They extract energy from their surroundings at a single particle level and use this to do work. Active matter is becoming an increasingly popular area of research because it provides a testing ground for the ideas of non-equilibrium statistical physics, because of its relevance to the collective behaviour of living creatures, from cells to starlings, and because of its potential in designing nanomachines. Dense active matter shows mesoscale turbulence, the emergence of chaotic flow structures characterised by high vorticity and self-propelled topological defects. I will discuss the physics of defects in active materials and describe examples where the concepts of active matter are starting to be used to describe cell sorting, motility and morphogenesis.

Seminarroom 1+2+3
03 Apr 2023
04:30 PM

Colloquium: Active Droplets

Prof. Annette Zippelius (Göttingen University)

Seminarroom 1+2+3
24 Apr 2023
04:30 PM

Colloquium: New Types of Interactions, Dynamics, and Emergent States in Active Systems

Cristián Huepe and Fernando Peruani (Northwestern University / CY Cergy Paris Université)

Seminarroom 1+2+3
08 May 2023
04:30 PM

Colloquium: Space-Time-Matter: Physics based on Finite Projective Geometry

Prof. Klaus Mecke (Friedrich-Alexander-Universität Erlangen)

Modern physics is based on the assumption that natural phenomena are consequences of force fields and elementary particles moving in a continuous spacetime, whose dynamics can mathematically be described by differential equations. An alternative to this substance ontology is the assumption that phenomena are processes of elementary events which are causally related so that space, time and matter properties emerge from fundamental process relations. This process ontology - proposed by Alfread North Whitehead - can mathematically be formulated as a finite projective geometry of event points where the dynamics is simply given by local quadratic forms, i.e. by a metric field. The task in physics remains to derive from this geometric structure the dynamical laws which are known to be empirically adaequate. To this end finite projective analogs of classical mechanics (time dependence), electrodynamics (spatial gauge fields) and quantum mechanics (random particle events) are formulated and their equivalence to the standard (analytical) theories is shown in the continuum limit. The origin of such important concepts as Legendre transform, gauge symmetry and commutator relations can be elucidated by basic features of finite projective geometry. Finally, the possibility is outlined of a unified theory of general relativity and quantum field theory of elementary particles, where finite projective geometry is the basic structure instead of a differentiable Riemannian manifold.

Seminarroom 1+2+3
22 May 2023
04:30 PM

Colloquium: Witnessing Many-Body Entanglement in Light-Driven Quantum Materials

Prof. Matteo Mitrano (Harvard University)

The ultrafast light-matter interaction is a powerful tool to control quantum materials’ properties and induce nontrivial dynamical states of matter such as transient superconductivity and Floquet topological phases. Crucial to the identification of these emergent phenomena is the concept of quantum coherence and our ability to distinguish genuine quantum correlations from fluctuations of randomized charge, spin, and orbital degrees of freedom. In certain systems, such as superconductors or certain quantum magnets, we can discriminate between incoherent and coherent processes by measuring specific order parameters. However, this approach cannot be easily generalized to more challenging forms of many-body entangled phases, such as quantum spin liquids. Is there an alternative way to diagnose the presence of quantum correlations in a light-driven material? In this talk, I will discuss how recent developments in the use of quantum metrology operators, called entanglement witnesses, open the possibility to probe many-body entanglement across photoinduced phase transitions. I will outline recent experimental and theoretical progress in quantifying spin entanglement in condensed matter systems and discuss how entanglement witnesses can be used to diagnose entanglement in systems with dynamically tuned electronic interactions. Finally, I will discuss how these methods can be applied to ultrafast optical and resonant inelastic x-ray scattering experiments, thus establishing a pathway to quantitative entanglement spectroscopy in quantum materials.

Seminarroom 1+2+3
12 Jun 2023
04:30 PM

Exploring the Universe with Gravitational Waves

Prof. Alessandra Buonanno (Max Planck Institute for Gravitational Physics, Department of Astrophysical and Cosmological Relativity)

For centuries, we have explored the Universe and discovered mysterious astrophysical sources and phenomena only through the observation of electromagnetic waves (gamma rays, X-rays, optical, infrared, radio waves). In 2015, we observed the first gravitational wave passing through the Earth produced by the merger of two stellar-mass black holes. Such an event has provided us with a remarkable confirmation of the general theory of relativity by Albert Einstein, and ushered in the era of gravitational-wave astronomy. Since then, about one hundred gravitational waves have been detected, including the gravitational signal produced by the coalescence of two neutron stars, accompanied by a plethora of electromagnetic counterparts observed by numerous telescopes around the world. In this talk I will describe how we decode the gravitational signals to trace the nature of the astrophysical source that emitted them, and discuss how the novel astronomical messengers are already unveiling distinctive properties of the most extreme astrophysical objects in the Universe: black holes and neutron stars. I will also highlight the bright future of gravitational-wave astronomy due to ever more sensitive detectors on the ground and in space, which will open new frequency bandwidths.

Seminarroom 1+2+3
19 Jun 2023
04:30 PM

Colloquium: Examples of Epithelium Dynamics

Prof. Jacques Prost (Institut Curie)

I will give examples of symmetry breakìng in epitheliums on substrates with several different topographies.

Seminarroom 1+2+3
03 Jul 2023
04:30 PM

Colloquium: Control of Attosecond and Strong Field Processes Using Structured Light

Prof. Carlos Hernández-García (Universidad de Salamanca)

Seminarroom 1+2+3
11 Jul 2023
04:00 PM

Price ceremony and colloquium "Physik-Preis Dresden 2023" - "Failed Theories of Superconductivity"

Prof. Dr. Jörg Schmalian (Karlsruhe Institute of Technology)

A historical account of pre-BCS attempts to understand superconductivity, embedded in some personal views on what fascinates me about the topic. It may have too little original research, but it is probably the most entertaining option.

Seminarroom 1+2+3
31 Jul 2023
04:30 PM

Colloquium: Design and Discover of New Correlated Electron Systems: Exploring New Materials Space

Prof. Paul C. Canfield (Iowa State University)

One of the apparent difficulties for New Materials Physics is how to identify promising phase spaces to explore or study. In essence, with hundreds of thousands of possible compounds (known and unknown) to consider, how can promising materials be discovered? The design and discovery of new strongly correlated electron systems or quantum materials is essentially a negotiation with Nature. As with any negotiation, it is important to be as flexible as possible while still holding on to the key points that are vital. In this talk I will try to illustrate how desires can be translated into specific new materials growth efforts. For example, how “wanting a low degeneracy, topological non-trivial compound that we could readily study with ARPES” can lead directly to the identification and study of RhBi2. Another example is how a desire to discover new quantum critical materials can be translated into searches near collapsed tetragonal phase transitions or the study of ternary compounds that include an immiscible pair of elements. NOTE: one of the goals of this talk it to provide my theoretical colleagues some insight into how experimentalists translate complex theoretical ideas into very primitive attempts to shave the dice in this cosmic game of craps.

Seminarroom 1+2+3
14 Aug 2023
04:30 PM

Colloquium: Exceptional non-Hermitian topology

Prof. Flore Kunst (Max Planck Institute for the Science of Light)

While topological phases of matter have predominantly been studied for isolated Hermitian systems, a recent shift has been made towards considering these phases in the context of non-Hermitian Hamiltonians. Non-Hermitian topological phenomena reveal an enrichment of the phenomenology of topological phases, and forms a rapidly growing new cross-disciplinary field. In particular, non- Hermiticity plays a central role in both classical and quantum systems. In the classical realm, this comes about due to, e.g., gain and loss processes in optics, while in the quantum realm, non-Hermiticity describes the dynamics of open quantum systems as well as scattering, decay, broadening and resonances due to, e.g., interactions and disorder. Non-Hermitian Hamiltonians may feature many exotic properties, which are radically different from their Hermitian counterparts, such as the generic appearance of exotic exceptional structures, a break down of the famed bulk-boundary correspondence, and the piling up of bulk states at the boundaries known as the non-Hermitian skin effect. In this talk, I will provide an overview of the field focussing on fundamental aspects, experimental realizations and I will briefly touch upon applications.

Seminarroom 1+2+3
21 Aug 2023
04:30 PM

Colloquium: Computer Simulations of Nuclear Quantum Effects in Molecular and Condensed Matter Systems

Prof. Xinzheng Li (Peking University)

Molecular and condensed matter systems are entities composed by interacting electrons and nuclei. An ideal computer simulation needs to address both the electronic and the nuclear systems accurately, as well as their couplings. Compared with the more and more accurate quantum treatments of the interacting electronic systems nowadays, theoretical descriptions of the nuclei still largely remain at the classical level. In this talk, I will explain some of our computer simulation results of nuclear quantum effects in molecular and condensed matter systems, including the quantum nature of hydrogen bonds [1-2], the quantum tunneling of hydrogen and water molecules [3-4], the quantun nature of the nuclei in high-pressure hydrogen [5-6], and the tunneling splitting of water clusters [7]. The basic technique we use is ab initio path-integral molecular dynamics. To accomadate the requirements associated with some specific problems, it was combine it with different computer simulation methods in each case. [1] Xin-Zheng Li, Brent Walker, and Angelos Michaelides, PNAS 108, 6369 (2011) [2] Jing Guo, Jingtao Lü, Yexin Feng, Ji Chen, Jinbo Peng, Xiangzhi Meng, Zhichang Wang, Zeren Lin, Xin-Zheng Li*, Enge Wang*, Ying Jiang*, Science 352, 321 (2016) [3] Wei Fang, Jeremy O. Richardson*, Ji Chen, Xin-Zheng Li*, and Angelos Michaelides*, Phys. Rev. Lett. 119, 126001 (2017) [4] Wei Fang, Ji Chen, Philipp Pedevilla, Xin-Zheng Li*, Jeremy O. Richardson*, and Angelos Michaelides*, Nat. Commun. 11, 1689 (2020) [5] Ji Chen, Xin-Zheng Li*, Qianfan Zhang, Matthew I. J. Probert, Chris J. Pickard, Richard J. Needs, Angelos Michaelides, and Enge Wang*, Nat. Commun. 4, 2064 (2013) [6] Xiaowei Zhang, Enge Wang*, and Xin-Zheng Li*, Phys. Rev. B 98, 134110 (2018) [7] Yu-Cheng Zhu, Shuo Yang, Jia-Xi Zeng, Wei Fang, Ling Jiang, Dong H. Zhang,* and Xin-Zheng Li*, J. Am. Chem. Soc. 144, 21356 (2022)

Seminarroom 1+2+3
28 Aug 2023
04:30 PM

Colloquium: Extreme Waves in Science and Engineering

Prof. Amin Chabchoub (Kyoto University)

Breather solutions of the nonlinear Schrödinger equation, also referred to as solitons on finite and continuous background, have been known since the late 70s. Some of these pulsating localized structures describe the nonlinear stage of the modulation instability in a variety of nonlinear dispersive media and are prized to model and control rogue wave events in such wave systems. The talk will elaborate on the latest groundbreaking breather observations in optics, hydrodynamics, plasma, and Bose-Einstein condensates. A particular focus will be devoted to applications, for instance in marine engineering as well as ocean rogue wave modeling and prediction. Moreover, perspectives on implementations and limitations of breather modeling for extreme sea waves will also be discussed.

Seminarroom 1+2+3
04 Sep 2023
04:30 PM

Colloquium: t.b.a.

Seminarroom 1+2+3
11 Sep 2023
04:30 PM

Colloquium: Exploring Human Creativity and AI for Engineered Quantum Matter

Prof. Eliška Greplová (TU Delft)

In research labs worldwide, quantum physics is making unprecedented strides. The realization of robust quantum systems holds tremendous promise for applications in secure communication and computing. Yet, as physicists, our most exciting pursuit lies in experimentally testing quantum phenomena predicted over the past century within highly controlled environments. In this colloquium, I will explore two distinct approaches to engineering quantum matter: one fueled by human creativity and the other driven by artificial intelligence. Throughout the colloquium, we will uncover how these approaches can be effectively deployed in contemporary quantum experiments, paving the way for advancements in our understanding and control of quantum phenomena.

Seminarroom 1+2+3
25 Sep 2023
04:30 PM

Colloquium: Interactions and Topology in Materials with Flat Bands: Superconductivity, Magnetism, and Fractional Chern Insulators

Prof. Bogdan Bernevig (Priceton University)

We will review remarkable recent progress in both experimental and theoretical research on flat bands materials. When a system exhibits flat bands despite having sizable hopping integrals/electron itineracy, the flat band is likely to be topological. In stoichiometric materials, one now has flat band catalogues of materials exhibiting such electronic states at the Fermi level. I will review the interacting and topological physics of such bands, first with simple one-body models and then adding interactions to obtain Kondo physics, magnets, charge density waves, and superconductors. In engineered moire materials, where the Fermi level can be gate-tuned, a new degree of precise controllability allows for the development of flat bands exhibiting Chern insulators, Superconductivity, and - most recently - Fractional Chern insulators. We will show that the physics of most of these bands holds a close resemblance to heavy Fermion physics.

Seminarroom 1+2+3
02 Oct 2023
04:30 PM

Colloquium: t.b.a.

Seminarroom 1+2+3
16 Oct 2023
04:30 PM

Colloquium: Modelling Critical Thresholds in Ice Sheets

Prof. Marisa Montoya (Universidad Complutense de Madrid)

Seminarroom 1+2+3
30 Oct 2023
04:30 PM

Colloquium: t.b.a.

Seminarroom 1+2+3
27 Nov 2023
04:30 PM

ATOM23 Colloquium: Attosecond Physics: 2023 Nobel Prize Achievements and Unraveling Quantum Insights

Prof. Lars Bojer Madsen (Aarhus University)

In my talk, I will start by giving an overview of this year’s Nobel Prize in Physics awarded to Anne L'Huillier, Ferenz Krausz and Pierre Agostini “for experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter”. Following their pioneering works, we have witnessed a revolutionary development of attosecond light sources, and methods to conduct attosecond time-resolved measurements. These now allow researchers to explore electron dynamics at this timescale, including charge migration in molecules and ultrafast processes in semiconductors and dielectrics. While experimental techniques have progressed rapidly, theory has not developed at the same pace. Insights that can be derived from present-day theory formulated in terms of single-electron and classical modeling are reaching their barrier. This situation impedes a deeper understanding of the quantum motion of electrons in matter and the quantum properties of light. Therefore, in the second part of my talk, I will discuss the challenges faced by current theoretical models and discuss ongoing efforts to enhance them. Three key areas of focus include (i) Electron-electron correlations: Exploring ways to incorporate electron-electron correlation in theoretical frameworks and identify their effect, (ii) Relativistic corrections: accounting for relativistic corrections is needed to provide a more accurate description of electron motion (iii) Beyond classical treatment of light: Going beyond a classical description of the electromagnetic fields to better capture the quantum nature of light, and explore the merging of quantum optics and strong-field laser physics.

Seminarroom 1+2+3
11 Dec 2023
04:30 PM

Gutzwiller Colloquium: Hydration in Bio-Nano Complex Matter

Giancarlo Franzese (Department of Condensed Matter Physics and Institute of Nanoscience and Nanotechnology, Universitat de Barcelona, Barcelona, Spain)

Water is a crucial element for life. However, there is still debate on why it is so important. This is because the mechanisms that control the effect of water on biological and nanoscopic solutes still need to be fully understood. Additionally, the challenges of renewable energy sources and water pollution are two major environmental concerns that need addressing: hydrated nano-interfaces could offer new solutions for applications such as desalination, decontamination, energy storage, and heterogeneous catalysis for green hydrogen production. This Colloquium will provide a broad introduction to these topics, connecting them with the unique properties of water [1, 2, 3]. Using Statistical Physics to create phenomenological models and multiscale computation can fill the knowledge gap and guide us toward new applications. For instance, it is possible to understand how hydration water modulates the folding, condensation, aggregation, and adsorption of proteins in solutions onto nanomaterials [4, 5]. This is a crucial element in designing new drugs or drug-delivery nanomedical devices. Another example is how this approach provides a way to explore the feasibility of using graphene nano-sponges and slit-pores for the physical filtration of water from pollutants [6, 7]. [1] Coronas, L. E., Vilanova, O., Bianco, V., de los Santos, F., and Franzese, G., The Franzese-Stanley Coarse Grained Model for Hydration Water, in 'Properties of Water from Numerical and Experimental Perspectives', Martelli, F. ed. (CRC press, Boca Raton 2022). [2] Skarmoutsos, I., Franzese, G., and Guardia, E., Using Car-Parrinello simulations and microscopic order descriptors to reveal two locally favored structures with distinct molecular dipole moments and dynamics in ambient liquid water, Journal of Molecular Liquids 364, 119936 (2022). [3] Abella, D., Franzese, G., and Hernández-Rojas, J., Many-Body Contributions in Water Nanoclusters, ACS Nano 17, 1959 (2023). [4] March, D., Bianco, V., and Franzese, G., Protein Unfolding and Ag- gregation near a Hydrophobic Interface, Polymers 13, 156 (2021). [5] Dura-Fauli, B., Bianco, V., and Franzese, G., Hydrophobic Homopolymer’s Coil–Globule Transition and Adsorption onto a Hydrophobic Surface under Different Conditions, The Journal of Physical Chemistry B 127 5541-5552 (2023). [6] Leoni, F., Calero, C., and Franzese, G., Nanoconfined Fluids: Uniqueness of Water Compared to Other Liquids, ACS Nano 15, 19864 (2021). [7] Bellido-Peralta, R., Leoni, F., Calero, C., and Franzese, G., Exploring optimal graphene slit-pore width for the physical separation of water-methanol mixture, The Journal of Molecular Liquids 391, 123356 (2023)

Seminarroom 1+2+3
31 Jan 2022
04:30 PM

Colloquium: Open Floquet Systems

Prof. André Eckardt (TU Berlin)

Floquet engineering is the idea to use time-periodic driving to coherently control quantum systems, so that they acquire novel properties that are hard or even impossible to achieve in non-driven systems. In isolated systems, this is achieved by engineering drives to shape the one-cycle evolution operator describing the stroboscopic evolution of the system in steps of the driving period. Often (unless the system is integrable or localized) the desired properties can only be achieved approximately, on a prethermal time scale, before the system eventually heats up to infinite temperature. Dissipative Floquet systems, which are coupled to an environment, instead approach non-equilibrium steady state (NESS) in the long-time limit. The properties of these states are determined (or controlled) by the interplay (and engineering) of driving and dissipation, opening the door for a robust form of dissipative Floquet engineering. I will give a basic introduction to these concepts and provide some examples of how steady (and also transient) states of open Floquet systems can be engineered.

28 Feb 2022
04:30 PM

Colloquium: Climate Meets Complex Systems: Exploring Predictability of Extreme Climate Events via a Complex Network Approach

Prof. Jürgen Kurths (Potsdam Institute for Climate Impact Research)

The Earth system is a very complex and dynamical one basing on various feedbacks. This makes predictions and risk analysis even of very strong (sometime extreme) events as floods, landslides, or heatwaves a challenging task. After introducing physical models for weather forecast already in 1922 by L.F. Richardson, a fundamental open problem has been the understanding of basic physical mechanisms and exploring anthropogenic influences on climate. In 2021 Hasselmann and Manabe got the Physics Nobel Price for their pioneering works on this. I will shortly review their main seminal contributions. Next, I will discuss a recently developed approach via complex networks mainly to analyze strong climate events. This leads to an inverse problem: Is there a backbone-like structure underlying the climate system? To treat this problem, we have proposed a method to reconstruct and analyze a complex network from spatio-temporal data. This approach enables us to uncover relations to global and regional circulation patterns in oceans and atmosphere, which leads to construct substantially better predictions of extreme climate events, in particular for the Indian Summer Monsoon, extreme rainfall in South America, the Indian Ocean Dipole, El Nino and tropical cyclones.

Seminarroom 4
21 Mar 2022
04:30 PM

Colloquium: A Mind Over Matter: The Life and Science of Philip W. Anderson

Prof. Andrew Zangwill (Georgia Institute of Technology)

This colloquium presents a biographical survey of the life and science of the Nobel laureate Philip W. Anderson, arguably the most influential physicist of the second half of the twentieth century. I discuss his upbringing during the American Great Depression, his education at Harvard University, his service during World War II, and his subsequent career as a condensed matter physicist at Bell Laboratories, Cambridge University, and Princeton University. I highlight some of his best-known scientific achievements and also some of his forays into national and scientific politics. A few remarks about his activities as a public intellectual and his personal life round out the talk.

11 Apr 2022
04:30 PM

Colloquium: Disorder-robust Phase Crystal in High-temperature Cuprate Superconductors from Topology and Strong Correlations

Prof. Annica Black-Schaffer (Department of Physics and Astronomy, Uppsala University)

The simultaneous interplay of strong electron-electron correlations, topological zero-energy states, and disorder is still a largely unexplored territory but of considerable interest due to their inevitable presence in many materials. Copper oxide high-temperature superconductors (cuprates) with pair breaking edges host a flat band of topological zero-energy states, making them an ideal playground where strong correlations, topology, and disorder are strongly intertwined. Here we perform fully self-consistent calculations of the superconducting state in cuprate superconductors and find that strong correlations stabilize a fully gapped phase crystal state along the pair breaking [110] edge. The phase crystal breaks both translational and time reversal invariance and is characterized by a nanoscale modulation of the phase of the d-wave order parameter. In particular, we first show how strong correlations increase the number of zero-energy states for any uniform superconducting phase, contradicting simple topological arguments. Then, when allowing for a non-uniform solution, we find a cascade of phase transitions occurring at different temperatures: d-wave superconductivity occurs below a transition temperature $T_c$, the phase crystal appears further below at temperature $T^* \sim 0.2 T_c$, and, finally, an additional extended s-wave order, with the same spatial modulations as the phase crystal, is generated below $T_s$, producing a full energy gap. Taken together, these phase transitions explain a set of so far seemingly contradictory experimental results. Furthermore, we find that the phase crystal state is unexpectedly very robust to disorder, but notably only in the presence of strong correlations. Our results show that the combined effects of strong correlations and topology lead to the emergence of novel phases of matter that survives strong disorder in a highly non-intuitive manner.

02 May 2022
04:30 PM

Colloquium: Relativistic-like Electron Hydrodynamics in Dirac Semimetals

Prof. Igor Shovkovy (Arizona State University)

Electron quasiparticles in Dirac semimetals may exhibit a hydrodynamic regime under certain conditions. Since the corresponding quasiparticle fluid is relativistic-like, anomalous, and electrically charged, it has a range of unusual properties. Anomalous physics affects properties of low-energy collective modes, relativistic-like effects show up in novel instabilities, and the charged nature of the electron fluid is responsible for the strong suppression of convection. In this talk, I will review some of these unusual properties of the electron fluid in Dirac semimetals.

Seminarroom 1+2
16 May 2022
04:30 PM

Colloquium: Chimeras in Physics and Biology: Synchronization and Desynchronization of Rhythms

Prof. Eckehard Schöll (Technische Universität Berlin)

Rhythms influence our life in various ways, e.g., through heart beat and respiration, oscillating brain currents, life cycles and seasons, clocks and metronomes, pulsating lasers, transmission of data packets, and many others. The physics of complex nonlinear systems has developed methods to describe and analyze self-sustained oscillations and their synchronization in complex networks, which are composed of many components. Synchronized oscillations as well as completely asynchronous chaotic oscillations play a major role in many networks in nature and technology. For instance, the synchronous firing of all neurons in the brain represents a pathological state, like in epilepsy or Parkinson's disease, and should be suppressed, as well as the synchronous mechanical vibration of bridges. On the other hand, synchronization is desirable for the stable operation of power grids or in encrypted communication with chaotic signals. In networks composed of identical components, intriguing hybrid states ("chimeras") may form spontaneously, which consist of spatially coexisting synchronized and desynchronized domains, i.e., seemingly incongruous parts. This might be of relevance in inducing and terminating epileptic seizures, or in unihemispheric sleep which is found in certain migratory birds and mammals, or in cascading failures of the power grid.

13 Jun 2022
04:30 PM

Colloquium: Aspects of topological magnons in Kitaev and non-Kitaev honeycomb magnets

Prof. Yong-Baek Kim (University of Toronto)

We discuss various examples of topological magnons in quantum magnets on honeycomb lattice. These include topological magnons in generalized Kitaev models on two-dimensional honeycomb lattice and the corresponding thermal Hall transport, higher order magnon topology and hinge states in stacked honeycomb magnets, and Weyl/nodal magnons in Kitaev magnets on three-dimensional hyperhoneycomb lattice.

21 Jun 2022
04:30 PM

Colloquium: Self-organizing Reconfigurable Robot Collectives at the Micron-Scale

Metin Sitti (Max Planck Institute for Intelligent Systems Stuttgart)

Mobile microrobots, which can navigate, sense, and interact with their environment, could potentially revolutionize medicine and environmental remediation. Many self-organizing microrobotic collectives have been developed to overcome inherent limits in actuation, sensing, and manipulation of individual microrobots; however, reconfigurable self-organized collectives with robust transitions between behaviors are rare. Such systems that perform multiple functions are advantageous to operate in complex environments. Here, we present a versatile self-organizing robotic collective system at the microscale capable of on-demand reconfiguration to adapt to and utilize their environments to perform various functions at the air-water interface. Each microrobot is disc-shaped with a magnetic film coating to be oscillated and pulled using applied external magnetic field waveforms and gradients, respectively. Microrobots have magnetic, capillary and hydrodynamic interactions inducing various nonlinear coupled dynamics and dynamic self-assembly modes. Our system exhibits diverse modes ranging from isotropic to anisotropic behaviors and transitions between a globally driven and a novel self-propelling behavior. We show the transition between different modes in experiments and simulations, and demonstrate various functions, using the reconfigurability of our system to navigate, explore, and interact with the environment. Such versatile microrobot collectives with globally driven and self-propelled behaviors have significant potential in future medical and environmental applications.

11 Jul 2022
04:30 PM

Colloquium: Tracking Lymphocyte Clones through Tissues, Individuals and Time

Prof. Eline T. Luning Prak (University of Pennsylvania)

The DNA sequences of antibody and T cell receptor gene rearrangements can be used to trace clonally-related lymphocytes through different tissues, in different individuals and over time. In this presentation, I will describe methods for inferring clonal relatedness from adaptive immune repertoire profiling data. I will describe networks of clones in different tissues of human organ donors and show how features of gene rearrangements yield insights into tissue compartmentalization of immune responses. I will also discuss some of our recent data on antibody responses to SARS-CoV-2 vaccines, highlighting how clonal lineage analysis can be used to understand how antibody responses evolve over time. Finally, I will describe some of our recent efforts to study shared repertoire features between individuals.

18 Jul 2022
04:30 PM

Colloquium: Researching Living Systems by Considering Modes of Change and Not Endpoints

Prof. Uri Hershberg (University of Haifa)

Seminarroom 1+2
01 Aug 2022
04:30 PM

Quantum simulation with ultracold atoms – from Hubbard models to gauge theories

Prof. Monika Aidelsberger (LMU Munich)

Well-controlled synthetic quantum systems, such as ultracold atoms in optical lattices, offer intriguing possibilities to study complex many-body problems in regimes that are beyond reach using state-of-the-art classical computations. The basic idea is to construct and use a well-controlled quantum many-body system in order to study its in- and out-of-equilibrium properties and potentially use it to develop more efficient tailored numerical methods that can then be applied to other systems that are not directly accessible with the simulator. An important future quest concerns the development of novel experimental techniques that allow us to expand the range of models that can be accessed. I will demonstrate this using the example of topological lattice models, which in general do not naturally appear in cold-atom experiments. I will show how the technique of periodic driving, also known as Floquet engineering, facilitates their realization and show how charge-neutral atoms in lattices can mimic the behavior of charged particles in the presence of an external magnetic field. A key ingredient for quantum simulation is the degree of control one has over the individual particles and the microscopic parameters of the model. We have recently succeeded to not only use the technique of periodic driving to emulate physical systems that we know exist in nature, but to take this idea one step further and realize completely new topological regimes that do not have any static analog. Moreover, we are currently developing a novel hybrid optical lattice platform, where tightly focused optical tweezers are used to locally control the motion of the atoms in the lattice, paving the way towards quantum simulation of simplified lattice gauge theories, which play a fundamental role in a variety of research areas including high-energy physics and topological quantum computation.

29 Aug 2022
04:30 PM

Colloquium: Quantum Transport and Dissipation of Superfluid Fermi Gases in Structured Optical Potentials

Dr. Giacomo Roati (European Laboratory for Nonlinear Spectroscopy (LENS), Ultracold Quantum Gases group)

I will report on the realization of supercurrents in homogeneous, tunable fermionic rings. We gain exquisite, rapid control over quantized persistent currents in all regimes of the BCS-BEC crossover through a universal phase-imprinting technique. High-fidelity read-out of the superfluid circulation state is achieved by exploiting an interferometric protocol, which also yields local information about the superfluid phase around the ring. In the absence of externally introduced perturbations, we find the induced metastable supercurrents to be as long-lived as the atomic sample. We trigger and inspect the supercurrent decay by inserting a single small obstacle within the ring. For circulations higher than a critical value, the quantized currents dissipate via the emission of vortices. Our results demonstrate fast and accurate control of quantized collective excitations in a macroscopic quantum system, and establish strongly interacting fermionic superfluids as excellent candidates for atomtronic applications.

Seminarroom 1+2
08 Sep 2022
04:30 PM

Colloquium: The Softest Crystals

Prof. Randall Kamien (University of Pennsylvania)

Usually, crystals have three-dimensional periodicity. Smectic liquid crystals, however, have one-dimensional order, even in three-dimensional samples. These systems, as simple as they might seem, connect the physics of biomembranes, superconductivity, and even special relativity. I will provide an introduction for non-specialists and show how this diverse set of ideas comes together in these very, very soft systems.

Seminarroom 1
12 Sep 2022
04:30 PM

Colloquium: The Observable Fingerprints of Network Dynamics

Prof. Baruch Barzel (Bar-Ilan University, Israel)

Seminarroom 1+2+3
19 Sep 2022
04:30 PM

Colloquium: Trapped and Measured

Prof. Francis Robicheaux (Purdue University)

Atoms made of a particle and an antiparticle are unstable, usually surviving less than a microsecond. Antihydrogen, the bound state of an antiproton and a positron, is made entirely of antiparticles and is believed to be stable. It is this longevity that holds the promise of precision studies of matter-antimatter symmetry. I will give an overview of the ALPHA experiment (with an emphasis on the physical processes involved in the measurements) which has succeeded in trapping antihydrogen in a cryogenic Penning trap for times up to 15 minutes and has successfully performed precision measurements of several properties of antihydrogen. For example, we have measured the 1S-2S frequency to about one part in a trillion. I will conclude with prospects for future precision measurements.

Seminarroom 1+2+3
07 Nov 2022
04:30 PM

Colloquium: Bacteria as Multicellular Organisms - History and Perspectives

Prof. Roberto Kolter (Harvard Medical School)

Seminarroom 1+2+3
21 Nov 2022
04:30 PM

Chromatin at Small and Large Scales

Prof. Helmut Schießel (Physics of Life, TU Dresden)

DNA molecules with a total length of two meters contain the genetic information in every cell in our body. To control access to the genes and to organize its spatial structure in the nucleus the cell makes use of sophisticated physical mechanisms. Base pair sequences multiplex various layers of information, chromatin remodelers mobilize nucleosomes via twist defects, and biomolecular condensates concentrate proteins and nucleic acids in specialized membraneless compartments. In this talk I discuss our current state of understanding of some of these physical mechanisms that influence the organization of the genetic material in space and time.

Seminarroom 4
12 Dec 2022
04:30 PM

Microfluidic Island Biogeography — Jam and Conquer

Prof. Oskar Hallatschek (University of Leipzig)

Microbes often colonize spatially-constrained habitats, such as pores in the skin or crypts in the colon. The resulting micro-communities can be very stable and contribute to the long-term function of our microbiomes. Due to a lack of spatio-temporal observations, it is however unclear how these communities and their ecological functions arise. Using microfluidic devices to systematically vary ecological correlation lengths, we uncover sharp transitions between different colonization states with different evolutionary properties. Our results show that density-dependent passive diffusion can drive reproducing populations to a jamming threshold, which entails supreme resilience against invaders at the cost of a total loss of mixing and intra-species competition. These results elucidate how cell proliferation can drive unique non-equilibrium phase transitions (different from MIPS). The emerging sensitivity to scale, foreshadowed in the field of island biogeography, underscores the need to control for scale in microbial eco-evolutionary experiments.

Seminarroom 4
11 Jan 2021
02:30 PM

Colloquium: A Case for Carbon Dioxide Removal from Air

Prof. Jennifer Wilcox (University of Pennsylvania, USA)

As a global society we have been burning fossil fuels to meet our energy and transportation needs since the start of the industrial revolution. This has resulted in atmospheric CO2 concentrations much greater than at any other time during the last 650,000 years. That concentration reached a record 415 parts per million in May 2019. The replacement of fossil fuels with renewables, advances in energy efficiency, and carbon capture and storage are among the key strategies required to prevent warming beyond 2°C within this century. But they will not be enough. We need to ramp up our efforts in reducing CO2 emissions, and then we need to do even more. The Earth’s natural systems, such as forests and oceans, are capable of removing roughly half of global CO2 emissions each year, while the rest steadily accumulates in the atmosphere. Until now, our best approach to avoiding the worst impacts of climate change was simply to avoid such emissions in the first place. But because of our failure to act quickly and at a large enough scale, we are now faced with the need to go beyond that strategy—to actually start removing CO2 directly from the air. Trees and oceans already do this, but these systems are overwhelmed. Manufactured or synthetic removal systems are designed to pull CO2 from the atmosphere, and at a much faster rate than natural systems. This talk will review both the promise and pitfalls of this approach.

18 Jan 2021
04:30 PM

Catching and reversing a quantum jump mid-flight

Michel Devoret (Yale University)

Measurements in quantum physics, unlike their classical physics counterparts, can fundamentally yield discrete and random results. Historically, Niels Bohr was the first to hypothesize that quantum jumps occurred between two discrete energy levels of an atom. Experimentally, quantum jumps were directly observed many decades later in an atomic ion driven by a weak deterministic force under strong continuous energy measurement. The times at which the discontinuous jump transitions occur are reputed to be fundamentally unpredictable. Despite the non-deterministic character of quantum physics, is it possible to know if a quantum jump is about to occur? Our work1 provides a positive answer to this question: we experimentally show that the jump from the ground state to an excited state of a superconducting artificial three-level atom can be tracked as it follows a predictable “flight” by monitoring the population of an auxiliary energy level coupled to the ground state. The experimental results demonstrate that the evolution of the jump — once completed — is continuous, coherent, and deterministic. Based on these insights and aided by real-time monitoring and feedback, we then pinpoint and reverse one such quantum jump “mid-flight”, thus deterministically preventing its completion. Our findings, which agree with theoretical predictions essentially without adjustable parameters, lend support to the modern formulation of quantum trajectory theory; most importantly, they may provide new ground for the exploration of real-time intervention techniques in the control of quantum systems, such as the early detection of error syndromes. 1. Z. Minev et al., Nature 570, 200–204 (2019)

01 Feb 2021
04:30 PM

Colloquium: tba

Seminarroom 1+2
01 Mar 2021
04:30 PM

Colloquium: Exoplanets and the Search for Atmospheric Biosignature Gases

Sara Seager (MIT)

Thousands of exoplanets are known to orbit nearby stars and small rocky planets are established to be common. Driving the field is the study of exoplanet atmospheres, with the goal of detecting a gas that might be indicative of life. A suitable “biosignature gas” is not just one that might be produced by life, but one that: can accumulate in an atmosphere against atmospheric radicals and other sinks; has strong atmospheric spectral features; and has limited abiological false positives. Which gases might be potential biosignature gases in an as yet unknown range of exoplanetary environments? New computer simulations and next-generation telescopes coming online means the ambitious goal of searching for “biosignature gases” in a rocky exoplanet atmosphere is within reach.

08 Mar 2021
04:30 PM

Colloquium: Leaving the physical corner: Tensor network methods augmented by mode transformations in molecular quantum chemistry and condensed matter physics

Jens Eisert (FU Berlin)

Tensor network methods have become workhorses in the study of strongly correlated systems in condensed matter physics and increasingly also in the context of molecular systems. While their variational character provides results of remarkable accuracy, the capture quantum states featuring low entanglement well, a set of states often referred to as the 'physical corner'. While this physical describes ground states of local Hamiltonian problems from the condensed matter context well, the same cannot be said for problems involving molecules in quantum chemistry or systems undergoing time evolution. In this talk I will provide an overview over tensor network methods augmented by fermionic mode transformations in the context of molecular problems [1], condensed-matter simulations [2], and time evolution [3]. If time allows, I might briefly mention two new applications of tensor networks in being a design principle for building quantum devices [4] and in machine learning [5,6]. [1] Fermionic orbital optimisation in tensor network states (C. Krumnow, L. Veis, Ö. Legeza, J. Eisert, Phys. Rev. Lett. 117, 210402 (2016)) [2] Towards overcoming the entanglement barrier when simulating long-time evolution (C. Krumnow, J. Eisert, Ö. Legeza, arXiv:1904.11999) [3] Dimension reduction with mode transformations: Simulating two-dimensional fermionic condensed matter systems (C. Krumnow, L. Veis, J. Eisert, Ö. Legeza, arXiv:1906.00205) [4] Simulating topological tensor networks with Majorana qubits (C. Wille, R. Egger, J. Eisert, A. Altland, Phys. Rev. B 99, 115117 (2019)) [5] Expressive power of tensor-network factorizations for probabilistic modeling, with applications from hidden Markov models to quantum machine learning, I. Glasser, R. Sweke, N. Pancotti, J. Eisert, J. I. Cirac, arXiv:1907.03741, NeurIPS (2019)) [6] Tensor network approaches for learning non-linear dynamical laws (A. Goessmann, M. Goette, I. Roth, G. Kutyniok, J. Eisert, R. Sweke, Submitted to ICML2020 (2020))

29 Mar 2021
04:30 PM

Colloquium: Maxwell in Chains

Martin Zirnbauer (Universität Köln)

In standard text books on electrodynamics, Maxwell's laws are often illustrated using field lines -- a notion that lacks relativistic covariance and obscures the superposition principle (see e.g. R. Feynman in: The Feynman Lectures on Physics, Vol II, Chapter 1-5). In this colloquium, an improved variant of the field line picture is presented: the discrete approximation of the electromagnetic field by chains (B and D are modeled as 1-chains, E and H as 2-chains). The language of chains offers a simple, direct and intuitive approach to Maxwell's electrodynamics, without compromising physical or mathematical correctness. Fundamental aspects such as parity invariance or the transcription of the theory to curved space-time are especially transparent in this approach. The talk illustrates the chain picture at a number of examples including vortex motion in superconductors, spin-orbit coupling, equivalence between problems of magneto- and electrostatics, emission of an electromagnetic signal by the discharge of a capacitor, quantum Hall-Ohm law. The colloquium is an outgrowth of the speaker's 30 years of experience teaching electrodynamics to physics students.

19 Apr 2021
04:30 PM

WS Colloquium: Unconventional superconductivity

Brad Ramshaw (Cornell University (USA))

Superconductivity comes in a wide variety of incarnations including conventional s-wave, high-Tc d-wave, and topological p-wave. While these states are well defined theoretically, they are extremely difficult to distinguish experimentally: all superconductors have Cooper pairs, a Meissner effect, and a zero-resistance state, while any differences between states are subtle. I will give an overview of the experimental situation with a particular focus on how to find a bulk, three-dimensional topological superconductor, drawing on my own group's research on Sr2RuO4 and UTe2.

03 May 2021
04:30 PM

Colloquium talk: What to do with a near-term quantum computer?

Alán Aspuru-Guzik (University of Toronto)

In 2019, Google researchers carried out an experiment where they achieved "quantum supremacy". This is defined as when a quantum computer performs *any* task in a way that a classical computer takes impractical amounts of time to simulate its outcome. This is a huge milestone for the field, but several milestones lie ahead. In this talk, I will describe a potential algorithmic road to "quantum advantage", ie. the moment when a quantum computer carries out a *practical* task on a system that is unreachable by current classical computers. To reach quantum advantage presumably many years of hardware development and algorithmic development lie ahead of us. The current era of quantum computing, coined near-term intermediate-scale quantum computing (NISQ) by John Preskill presents many challenges and opportunities. I will discuss this algorithmic road in the context of algorithms for the simulation of molecules and materials, as well as will briefly mention quantum machine learning applications.

07 Jun 2021
04:30 PM

Colloquium: May's Instability in Firm Networks

Jean-Philippe Bouchaud (Capital Fund Management S.A., Frankreich)

Will a large economy be stable? Building on Sir Robert May’s original argument for large ecosystems, we conjecture that evolutionary and behavioural forces conspire to drive the economy towards marginal stability. We study networks of firms in which inputs for production are not easily substitutable, as in several real-world supply chains. We argue that such networks generically become dysfunctional when their size increases, when the heterogeneity between firms becomes too strong, or when substitutability of their production inputs is reduced. At marginal stability and for large heterogeneities, we find that the distribution of firm sizes develops a power-law tail, as observed empirically. Crises can be triggered by small idiosyncratic shocks, which lead to “avalanches” of defaults characterized by a power-law distribution of total output losses. This scenario would naturally explain the well-known “small shocks, large business cycles” puzzle, as anticipated long ago by Bak, Chen, Scheinkman, and Woodford.

28 Jun 2021
04:30 PM

Gutzwiller Colloquium: Topological electrostatics

Benoît Douçot (LPTHE, Sorbonne University and CNRS, Paris)

Two-dimensional electron gases under a strong magnetic field have tremendously expanded our understanding of many-body physics, with the discovery of integer and fractional quantum Hall effects, together with chiral edge states, fractional excitations, anyons. Another striking effect is the strong coupling between charge and spin/valley degrees of freedom, which takes place near integer filling of the magnetic Landau levels. More precisely, because of the large energy gap associated to cyclotron motion, any slow spatial variation of the spin background induces a variation of the electronic density proportional to the topological density of the spin background. Minimizing Coulomb energy leads to an exotic class of two-dimensional crystals, which exhibit a periodic non-collinear spin texture called a Skyrmion lattice. I will review the history of these concepts, with an emphasis on the notions of Berry phases and Berry curvature, which play a prominent role in all aspects of topological condensed matter physics. A main feature of these Skyrmion crystals is that their theoretical description involves effective theories with local and possibly non-Abelian gauge symmetries. It is therefore a theoretical challenge to identify the actual physical degrees of freedom in such systems. I will show how this may be achieved using some ideas from complex geometry. The main outcome of such analysis is the existence of two regimes depending on whether the topological charge per unit cell is smaller (unfrustrated case) or larger (frustrated case) than the number of internal states (spin/valley) accessible to electrons.

Seminarroom 4
05 Jul 2021
04:30 PM

Virtual Coll.-Talk: Ductile and brittle yielding in sheared amorphous materials

Suzanne Fielding (Durham University, UK)

We discuss recent theoretical progress in understanding the nature of yielding in amorphous materials. Within an athermal elastoplastic model in quasistatic shear, we find that yielding is brittle in the limit of large system size, whatever the level of annealing/ageing of the sample prior to shear. For small systems, in contrast, we find a crossover from apparently ductile to brittle yielding behaviour with increasing degree of sample annealing prior to shear. Differences between studies in one and two spatial dimensions will be discussed. We will also compare the nature of ductile/brittle yielding in athermal materials with that in thermal materials.

06 Jul 2021
04:40 PM

Prize Colloquium "Physik-Preis Dresden 2021"

Prof. Gijsje Koenderink (Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology)

Cells and tissues are highly dynamic but at the same time need to withstand large mechanical loads. This paradoxical mechanical behavior is governed by fibrous protein scaffolds known as the cytoskeleton and the extracellular matrix. Fibrous networks have many advantageous mechanical properties: fibers can form space-filling elastic networks at low volume fractions and they reversibly stress-stiffen, which provides protection from damage. However, it is still poorly understood how biopolymer networks can combine these features with the ability to dynamically adapt their structure and mechanics. This question has guided our research over the past years. I will provide an overview of the most important things we have learned by performing quantitative measurements on reconstituted cytoskeletal and extracellular matrix networks. We perform these measurements from the macroscopic scale (using rheology) all the way down to the molecular scale (using optical tweezers, in situ small-angle-X-ray scattering, and atomic force microscopy). I will furthermore mention connections to applications in bottom-up synthetic biology and for tissue (re)generation.

19 Jul 2021
04:30 PM

Colloquium talk: Colliders, Higgs and the strong interaction

Gavin Salam (University of Oxford)

Particle colliders are our main laboratory tool to study the smallest distance scales accessible to humankind. Recent years have seen major advances, notably the discovery of long-hypothesised, but qualitatively new interactions in the Higgs sector, which are essential for a universe as we know it. Central to the progress of collider particle physics is our understanding of the strong interaction and its theoretical formulation, quantum chromodynamics. This rich theory operates across many orders of magnitude in distance and momentum, producing hundreds of particles in each collision. One of today's major challenges is to learn how to maximally and reliably exploit the resulting information.

13 Sep 2021
04:30 PM

Colloquium talk: A statistical physics view of cells under strong perturbations

Nathalie Balaban (Hebrew University of Jerusalem)

11 Oct 2021
04:30 PM

Hybrid Colloq-talk: Many-body chaos and order, through the lens of OTOCs

Roderich Moessner (MPI PKS)

The concepts of order and chaos are central to our understanding of the statistical mechanics of dynamical systems. Starting from the fabled butterfly effect, this talk presents a brief survey of general properties of chaotic many-body dynamics, in particular showing how out-of-time-ordered correlators (OTOCs) appear naturally there. It addresses such dynamics in simple and familiar model systems exhibiting different degrees of order, and concomitant descriptions with and without quasiparticle excitations. It finally demonstrates how OTOCs can be used in practise to mitigate errors in a noisy quantum computing platform. This is used to extract the intrinsic signal of a new type of spatiotemporal eigenstate order realised in a many-body localised discrete time crystal.

Seminarroom 4
18 Oct 2021
04:30 PM

Coll.-Talk: Vacuum fluctuations in cavities: breakdown of the topological protection in the integer Quantum Hall effect

Jérôme Faist (ETH, Zürich)

When a collection of electronic excitations are strongly coupled to a single mode cavity, mixed light-matter excitations called polaritons are created. The situation is especially interesting when the strength of the light-matter coupling WR is such that the coupling energy becomes close to the one of the bare matter resonance w0. For this value of parameters, the system enters the so-called ultra-strong coupling regime, in which a number of very interesting physical effects were predicted caused by the counter-rotating and diamagnetic terms of the Hamiltonian. In a microcavity, the strength of the electric field caused by the vacuum fluctuations, to which the strength of the light-matter coupling WR is proportional, scales inversely with the cavity volume. One very interesting feature of the circuitbased metamaterials is the fact that this volume can be scaled down to deep subwavelength values in all three dimension of space. Using metamaterial coupled to two-dimensional electron gases under a strong applied magnetic field [1], we have now explored to which extend this volume can be scaled down and reached a regime where the stability of the polariton is limited by diffraction into a continuum of plasmon modes [2]. We have also used transport to probe the ultra-strong light-matter coupling [3], and show now that the latter can induce a breakdown of the integer quantum Hall effect. [1] G. Scalari et al., "Ultrastrong Coupling of the Cyclotron Transition of a 2D Electron Gas to a THz Metamaterial," (in English), Science, vol. 335, no. 6074, pp. 1323-1326, Apr 15 2012, doi: 10.1126/science.1216022. [2] S. Rajabali, E. Cortese, M. Beck, S. D. Liberato, J. Faist, and G. Scalari, "Polaritonic nonlocality in light–matter interaction," Nature Photonics, vol. 15, no. 9, pp. 690-695, 2021, doi: 10.1038/s41566-021-00854-3. [3] G. L. Paravicini-Bagliani et al., "Magneto-transport controlled by Landau polariton states," (in English), Nature Physics, OriginalPaper vol. 15, no. 2, pp. 186-+, Feb 2019, doi: 10.1038/s41567-018-0346-y

25 Oct 2021
04:30 PM

Colloquium: Probabilistic cellular automata for quantum fermions

Prof. Dr. Christof Wetterich (Universität Heidelberg)

Fermions are often considered as somewhat strange quantum objects due to their anti-commuting properties. Cellular automata describe deterministic changes for bit-configurations, as for classical computing. At first sight these two issues do not seem to be much related. We show that probabilistic cellular automata, for which initial conditions are given by a probability distribution, can describe certain quantum many body systems of interacting fermions. The notions of wave functions, non-commuting operators for observables and quantum rules for expectation values arise in a natural way from the classical statistics for the probabilistic cellular automata. This constitutes an example how quantum mechanics can emerge from a classical statistical system. The famous particle-wave duality combines the discreteness of the bit observables or fermionic occupation numbers with the continuity of the probabilistic information and its evolution in time.

13 Dec 2021
04:30 PM

Rydberg spin liquids and beyond: Creating highly entangled quantum states in synthetic matter

Ashvin Vishwanath (Harvard)

In sharp contrast to ordered states such as crystals and magnets, entirely new patterns of quantum entanglement emerge in states with intrinsic topological order (ITO) such as fractional quantum Hall states and spin liquids. Their unique properties hold promise for a range of applications - most notably in the quest for fault-tolerant quantum computing. However, ITOs are notoriously hard to realize experimentally. For example, quantum spin liquids were proposed by Anderson in 1973 but remain to be clearly identified in any magnetic material. Key obstacles include the propensity towards order and the lack of clear signatures associated with ITO. Synthetic platforms, such as Rydberg atom arrays, with their high tunability and access to non-local `string' correlations can circumvent these barriers. In this talk, I will describe our theoretical proposal to create ITO in Rydberg atom arrays, methods to characterize their subtle signatures, and the experimental progress towards these goals. Finally, I will describe our ongoing exploration of new approaches utilizing measurement to efficiently realize many kinds of ITOs, including fractons, in synthetic matter.

20 Jan 2020
04:30 PM

Gutzwiller Colloquium: Birth, Death, and Flight: the hydrodynamics of Malthusian flocks

Prof. John Toner (University of Oregon, USA)

I'll present the hydrodynamic theory of ``Malthusian Flocks": moving aggregates of self-propelled entities (e.g., organisms, cytoskeletal actin, microtubules in mitotic spindles) that reproduce and die. Long-ranged order (i.e., the existence of a non-zero average velocity $\langle \bf{v} (\bf{r,t}) \rangle \neq \bf{0}$) is possible in these systems, even in spatial dimension $d=2$. Their spatiotemporal scaling structure can be determined exactly in $d=2$; furthermore, they lack both the longitudinal sound waves and the giant number fluctuations found in immortal flocks. Number fluctuations are very ${\it persistent}$, and propagate along the direction of flock motion, but at a different speed. I'll also present recent results for the three dimensional version of this problem, which required the first full blown dynamical renormalization treatment of a flocking system in its ordered phase.

Seminarroom 1+2+3
27 Jan 2020
04:30 PM

Colloquium: Quantum Spacetime from Causal Dynamical Triangulations

Prof. Dr. Renate Loll (Radboud University, Aj Nijmegen, Niederlande)

Causal Dynamical Triangulations (CDT) is a candidate theory for quantum gravity, formulated nonperturbatively as the scaling limit of a lattice theory in terms of piecewise flat (triangulated) spacetimes. From a technical and conceptual perspective, an important feature of this approach is its elegant resolution of the problem of how to treat the diffeomorphism symmetry of the classical theory in the full, background-free quantum theory. This has enabled the concrete computation of geometric observables in a highly nonperturbative, Planckian regime, an important step in putting quantum gravity on a quantitative footing, and understanding the structure of quantum spacetime. While the need to find quantum observables describing this regime is common to all approaches, CDT quantum gravity provides a concrete testing ground for implementation and measurements. In particular, a new notion of quantum Ricci curvature has opened a new window on some of the counterintuitive properties of quantum geometry.

Seminarroom 1+2
03 Feb 2020
04:30 PM

Colloquium: Ca$_2$RuO$_4$: correlated electron physics in a nutshell

Prof. Andrew J. Millis (Department of Physics, Columbia University and Center for Computational Quantum Physics, The Flatiron Institute, New York, USA)

The set of compounds (Ca/Sr)$_2$RuO$_4$ exhibit a rich array of properties, ranging from fermi liquid/Hunds metal physics and nontrivial superconductivity to metal-insulator transition that is driven by the interplay of correlated electron and lattice physics and is highly controllable by strain and current. Following a brief review of the material family, this talk will focus on the end-member Ca$_2$RuO$_4$, showing how attempts to understand the properties via multiple theoretical methods are leading to new insights into the techniques of many-body physics, how the metal insulator transition has provided new insights into the role of the lattice in correlated electron physics, and how the current-driven transition is providing new insights into nonequilibrium properties of correlated systems.

Seminarroom 1+2
17 Feb 2020
04:30 PM

Colloquium: Synthesizing “Toy Model” Quantum Materials

Prof. Joseph Checkelsky (Massachusetts Institute of Technology)

Connecting theoretical models for exotic quantum states to real physical systems is a key goal in the study of quantum materials. Among such theoretical models, a “toy model” is one made deliberately simplistic in order to demonstrate new physical concepts and their underlying mechanisms. Such models have proven to be tremendously successful in offering insight in to new condensed matter phenomena including those involving electronic topology and correlation. We describe here our recent progress in experimentally realizing “toy model” quantum materials which, in analogy to their theoretical counterparts, are designed to capture simple model systems by lattice and superlattice design. We detail developments in synthesizing and studying magnetic and superconducting materials that allow for new connections to long-standing predictions for unusual topological electronic phases. We close with a perspective for realizing further toy model systems in complex material structures.

Seminarroom 1+2
02 Mar 2020
04:30 PM

Colloquium: The scales that limit: biological scaling and the physical boundaries of evolution

Prof. Chris Kempes (Santa Fe Institute, New Mexico, USA)

Organisms are subject to the laws of physics, so the process of evolution is constrained by these fundamental laws. Classic and recent studies of the biophysical limits facing organisms have shown how fundamental physical constraints can be used to predict broad-scale relationships between body size and organismal biomechanics and physiology. In this talk I will provide a broad framework for the connection between physical constraints, evolution, and allometric physiology. I will focus on an under-appreciated aspect of allometry: ultimate limits that occur at distinct scales for broad categories of organisms. I will connect these limits to higher-order evolutionary phenomena such as major evolutionary transitions and constraints on populations of organisms. In discussing these concepts I will cover case-studies ranging from bacterial physiology to mammalian population dynamics, and I will outline a broad physics-based evolutionary theory.

Seminarroom 1+2
08 Jun 2020
04:30 PM

VIRTUAL Colloquium: Artificial intelligence: success and limits

Prof. Marc Mezard (Ecole Normale Supérieure, PSL University - Paris)

Artificial Intelligence is about to have a dramatic impact on many sectors of human activity. In the last ten years, thanks to the development of machine learning in “deep networks”, we have experienced spectacular breakthroughs in diverse applications such as automatic interpretation of images, speech recognition, consumer profiling, or go and chess playing. Algorithms are now competing with the best professionals at analyzing skin cancer symptoms or detecting specific anomalies in radiology; and much more is to come. Worrisome perspectives are frequently raised, from massive job destruction to autonomous decision-making “warrior” robots. In this talk, we shall open the black box of deep networks and explore how they are programmed to learn from data by themselves, using a statistical physics perspective. This will allow us to understand their limits, to underline the lack of theoretical understanding, to question whether their achievements have anything to do with “intelligence”, and to reflect on the foundations of scientific intelligence.

15 Jun 2020
04:30 PM

VIRTUAL Colloquium: Computational Epidemiology at the time of COVID-19

Prof. Alessandro Vespignani (Northeastern University, Boston, MA, USA)

The data science revolution is finally enabling the development of large-scale data-driven models that provide scenarios, forecasts and risk analysis for infectious disease threats. These models also provide rationales and quantitative analysis to support policy making decisions and intervention plans. At the same time, the non-incremental advance of the field presents a broad range challenges: algorithmic (multiscale constitutive equations, scalability, parallelization), real time integration of novel digital data stream (social networks, participatory platform, human mobility etc.). I will review and discuss recent results and challenges in the area, and focus on ongoing work aimed at responding to the COVID-19 pandemic.

10 Aug 2020
04:30 PM

Colloquium: Scaling down the laws of thermodynamics

Prof. Christopher Jarzynski (University of Maryland, USA)

Thermodynamics provides a robust conceptual framework and set of laws that govern the exchange of energy and matter. Although these laws were originally articulated for macroscopic objects, nanoscale systems also exhibit “thermodynamic¬-like” behavior – for instance, biomolecular motors convert chemical fuel into mechanical work, and single molecules exhibit hysteresis when manipulated using optical tweezers. To what extent can the laws of thermodynamics be scaled down to apply to individual microscopic systems, and what new features emerge at the nanoscale? I will describe some of the challenges and recent progress – both theoretical and experimental – associated with addressing these questions. Along the way, my talk will touch on non-equilibrium fluctuations, “violations” of the second law, the thermodynamic arrow of time, nanoscale feedback control, strong system-environment coupling, and quantum thermodynamics.

07 Sep 2020
04:30 PM

Colloquium: Dynamical Phase Transitions in Cold Atomic Gases

Dr. Ana Maria Rey (JILA/NIST University of Colorado, UCB, Boulder)

Non-equilibrium quantum many-body systems can display fascinating phenomena relevant for various fields in science ranging from physics, to chemistry, and ultimately, for the broadest possible scope, life itself. The challenge with these systems, however, is that the powerful formalism of statistical physics, which have allowed a classification of quantum phases of matter at equilibrium does not apply. Therefore, using controllable cold atomic systems to shed light on the organizing principles and universal behaviors of dynamical quantum matter is highly appealing. One emerging paradigm is the dynamical phase transition (DPT) characterized by the existence of a long-time-average order parameter that distinguishes two non-equilibrium phases. I will report the observation of a DPT in two different but complementary systems: a trapped quantum degenerate Fermi gas and long lived arrays of atoms in an optical cavity. I will show how these systems can be used to simulate iconic models of quantum magnetism with tunable parameters and to probe the dependence of their associated dynamical phases on a broad parameter space. Besides advancing quantum simulation our studies pave the ground for the generation of metrologically useful entangled states which can enable real metrological gains via quantum enhancement.

14 Sep 2020
04:30 PM

Colloquium: 3D Metamaterials: Rationally Designed Artificial Crystals

Prof. Dr. Martin Wegener (Karlsruher Institut für Technologie, KIT)

Metamaterials are rationally designed three-dimensional composites made of one or more bulk ingredient materials allowing for effective-medium properties going beyond (“meta”) those of the ingredient materials, qualitatively and/or quantitatively. In this talk, I focus on three-dimensional crystalline metamaterials. After an introduction into the concept, I discuss recent examples. This includes artificial cubic chainmail-like crystals leading to a sign reversal of the effective isotropic Hall coefficient, anisotropic crystals exhibiting the parallel Hall effect, chiral cubic crystals showing twist effects and acoustical activity forbidden in Cauchy elasticity, and cubic crystals exhibiting a sign reversal of the isotropic thermal expansion coefficient and a negative static effective compressibility, respectively.

21 Sep 2020
04:30 PM

Colloquium: The Sound of Fermions

Prof. Martin Wolfram Zwierlein (Massachusetts Institute of Technology, USA)

Transport is the defining property of states of matter, but often the most difficult to understand. Strongly interacting Fermi gases are especially challenging, despite their ubiquitous presence across many fields of physics, from atomic nuclei to high-temperature superconductors and neutron stars. Experiments on ultracold fermionic atoms allow the direct measurement of transport properties in ideal model systems where the Hamiltonian is precisely known, while transport properties are difficult to calculate theoretically. In this talk I will present our experiments on two systems: The unitary Fermi gas, where interactions are tuned to be as strong as quantum mechanics allows, and the Fermi-Hubbard lattice gas, believed to hold the key for our understanding of high-temperature superconductivity. Locally resolved sound and heat transport can distinguish superfluid and normal flow regimes in the unitary gas. Our observation of spin transport in the Fermi-Hubbard system reveals the mechanism governing quantum magnetism.

28 Sep 2020
04:30 PM

Colloquium: Landscape and generalisation in deep learning

Prof. Matthieu Wyart (Institute of Physics, Ecole Polytechnique Federale de Lausanne)

Deep learning is very powerful at a variety of tasks, including self-driving cars and playing go beyond human level. Despite these engineering successes, why deep learning works remains unclear; a question with many facets. I will discuss two of them: (i) Deep learning is a fitting procedure, achieved by defining a loss function which is high when data are poorly fitted. Learning corresponds to a descent in the loss landscape. Why isn’t it stuck in bad local minima, as occurs when cooling glassy systems in physics? What is the geometry of the loss landscape? (ii) in recent years it has been realised that deep learning works best in the over-parametrised regime, where the number of fitting parameters is much larger than the number of data to be fitted, contrarily to intuition and to usual views in statistics. I will propose a resolution of these two problems, based on both an analogy with the energy landscape of repulsive particles and an analysis of asymptotically wide nets.

19 Oct 2020
04:30 PM

Colloquium: Half-integer charge injection by a Josephson junction without excess noise

Prof. Dr. Carlo Beenakker (Universiteit Leiden, Niederlande)

A Josephson junction in a topological superconductor can inject a charge e/2 into a normal-metal contact, carried by chiral Majorana edge modes. We address the question whether this half-integer charge is a sharp observable, without quantum fluctuations. Because the Majorana modes are gapless, they support charge fluctuations in equilibrium at zero temperature. But we find that the excess noise introduced out of equilibrium by the e/2 charge transfer vanishes. We discuss a strategy to reduce the equilibrium fluctuations, by means of a heavy-tailed time-dependent detection efficiency, to achieve a nearly noiseless half-integer charge transfer.

23 Nov 2020
04:30 PM

Colloquium: From Entangled Quantum Puzzles to Quantum Information

Prof. Dr. Anton Zeilinger (Österreichische Akademie der Wissenschaften, Wien)

Entangled photons have become an essential workhorse for experiments on the foundations of quantum mechanics. Tests of Bell’s Inequality (cf. the Einstein-Podolsky-Rosen Paradox) have with increasing sophistication ruled out more and more alternative views to quantum mechanics. Besides that, they emerged to be also essential for a number of future quantum communication tasks. In most experiments, entanglement of two qubits, that is, of two photons in two states, e.f. polarization are employed. Going beyond two particles, and beyond two dimensions interesting novel phenomena arise. One of them is the GHZ contradiction, where a conflict between an objective local (i.e. classical) view in quantum mechanics arises even for non-statistical predictions of the theory. A most fascinating subject is entanglement swapping, where photons can be entangled which share no common past. In delayed-choice entanglement swapping, the decision whether two photons are entangled or not can be done at a time after they have already been detected and their measurement results (e.g. their polarization) has been registered. Going beyond qubits, states of orbital angular momentum (OAM) of photons provide an in principle unlimited discrete state space where the photons can also be entangled in many different ways. That way, entanglement has been confirmed for quantum numbers above 10.000 and between two photons, each carrying more than 100-dimensional states. A Cosmic Bell Test employed very distant quasars. Also, quantum communication was established between Europe and China using the Chinese satellite Micius. I will conclude with the Big Bell Test, an experiment to test quantum entanglement employing human free will with twelve laboratories on five continents and a hundred million human participants.

14 Dec 2020
01:30 PM

Colloquium: Strongly Interacting QCD Matter at Finite Temperature and Density

Prof. Tetsuo Hatsuda (RIKEN, Japan)

Quantum Chromodynamics (QCD) is the fundamental theory for elementary particles (quarks and gluons) which constitutes the proton, the neutron and the atomic nuclei. Because the quarks and gluons are strongly interacting, their arise characteristic phases at finite temperature and baryon density: The hadronic phase at low temperature and density with the non-perturbative phenomena such as confinement and chiral symmetry breaking, the quark-gluon plasma phase at high temperature and low density, and the superconducting quark matter at low temperature and high density. In this colloquium, I discuss the characteristic properties of these phases on the basis of the many-body approach to QCD as well as their relevance to the physics of early universe, accelerator experiments, neutron stars and gravitational waves.

21 Jan 2019
04:30 PM

Colloquium: Symmetry, topology and electronic phases of matter

Prof. Charles Kane (University of Pennsylvania, PA, USA)

Symmetry and topology are two of the conceptual pillars that underlie our understanding of matter. While both ideas are old, over the past several years a new appreciation of their interplay has led to dramatic progress in our understanding of topological electronic phases. A paradigm that has emerged is that insulating electronic states with an energy gap fall into distinct topological classes. Interfaces between different topological phases exhibit gapless conducting states that are protected and are impossible to get rid of. In this talk we will discuss the application of this idea to the quantum Hall effect, topological insulators, topological semimetals and topological superconductors. The latter case has led to the quest for observing Majorana fermions in condensed matter, which opens the door to proposals for topological quantum computation. We will close by surveying the frontier of topological phases in the presence of strong interactions.

Seminarroom 1+2
04 Feb 2019
04:30 PM

Colloquium: Simulating Condensed matter physics with light

Prof. Jacqueline Bloch (Centre de Nanosciences et de Nanotechnologies (C2N), Palaiseau, France)

When confining photons in semiconductor lattices, it is possible deeply modifying their physical properties. Photons can behave as finite or even infinite mass particles, photons inherit topological properties and propagate along edge states without back scattering, photons can become superfluid and behave as interacting particles. These are just a few examples of properties that can be imprinted into fluids of light in semiconductor lattices. Such manipulation of light present not only potential for applications in photonics, but great promise for fundamental studies. During the talk, I will illustrate the variety of physical systems we can emulate with fluids of light by presenting a few recent experiments: a photonic benzene molecule that emits helical photons, a photonic 1D lattice with topological edge states and photonic graphene with exotic Dirac cones. Perspectives in terms of quantum simulation will be discussed.

Seminarroom 1+2
18 Feb 2019
04:30 PM

Colloquium: Emergent configurational quantum matter created out of equilibrium in layered chalcogenides

Prof. Dragan Mihailovic (University of Ljubljana, Jozef Stefan Institute and Department of Physics, Slowenia)

The idea that many body systems in complex materials may self-organize under highly non-equilibrium conditions suggests that entirely new emergent states with new and unexpected functionalities might be created in this way. The route for creation of such states is not limited to symmetry-breaking phase transitions, and entirely novel mechanisms may come into play. I will discuss recent experimental findings of mesoscopically textured topologically protected metastable states created through density-driven non-equilibrium transitions. Combining ultrafast optical pulse excitation with scanning tunneling microscopy under various non-equilibrium conditions we find various intertwined electronic orders and metastable amorphous electronic states stabilized in real space by non-trivial topological defects. The relaxation of these states reveals a novel state of configurational quantum electronic matter that may find its uses in ultrafast memory devices.

Seminarroom 1+2
25 Feb 2019
04:30 PM

Colloquium: Fluctuations of Energy-Relaxation Times in Superconducting Qubits

Prof. John Martinis (Google and University of California, Santa Barbara)

Superconducting qubits are an attractive platform for quantum computing since they have demonstrated high-fidelity quantum gates and extensibility to modest system sizes. Nonetheless, an outstanding challenge is stabilizing their energy-relaxation times, which can fluctuate unpredictably in frequency and time. Here, we use qubits as spectral and temporal probes of individual two-level-system defects to provide direct evidence that they are responsible for the largest fluctuations. This research lays the foundation for stabilizing qubit performance through calibration, design, and fabrication.

Seminarroom 1+2
11 Mar 2019
04:30 PM

Colloquium: Non-hermitian topological photonics

Prof. Dr. Alexander Szameit (Universität Rostock, Institut für Physik)

The recent development of topological insulator states for photons1–3 has led to an exciting new field of “topological photonics,” which has as a central goal the development of extremely robust photonic devices4. Topological insulator physics has been studied extensively in condensed matter5 and cold atoms6. However, photonic systems offer the possibility of non-Hermitian effects through the engineering of optical gain and loss, which opens an entire new field of physics. In this talk, we will discuss our recent experimental work on non-Hermitian topological phenomena in coupled lattice systems, in particular the first demonstration of non-hermitian PT-symmetric topological interface state. References [1] Haldane, F. D. M. & Raghu, S., Phys. Rev. Lett. 100, 013904 (2008) [2] Wang, Z. et al., Nature 461, 772–775 (2009) [3] Rechtsman, M. C. et al., Nature 496, 196–200 (2013) [4] Hafezi et al., Nature Physics 7, 907-912 (2011) [5] Hasan, M. Z. & Kane, C. L., Rev. Mod. Phys. 82, 3045–3067 (2010) [6] Jotzu, G. et al., Nature 515, 237–240 (2014)

Seminarroom 1+2
08 Apr 2019
04:30 PM

Colloquium: Impurity states in superconductors and Dirac Materials

Prof. Alexander Balatsky (NORDITA, Stockholm, Schweden)

Impurity engineered states are the key component of modern electronics. We expect impurity engineered states will continue to be an important ingredient in quantum technologies beyond Si. New platforms that take advantage of impurity engineered bands such as superconductors and Dirac Materials are emerging. In this talk I will review the status and future perspectives of the field of impurity bound states in superconductors and will discuss striking similarities and important differences between defect states in superconductors and Dirac materials. I will highlight the recent progress made in our understanding of Yu-Shiba-Rusinov states in superconductors and topological states and illustrate the proposed induction of novel odd frequency Berezinskii pairing by YSR impurities. I will also discuss the universal nature of impurity resonances in unconventional SC and Dirac Materials and the implications these resonances have on functional properties of doped Dirac materials. Work supported by ERC, KAW and Villum Center for Dirac Materials.

Seminarroom 1+2
29 Apr 2019
04:30 PM

Colloquium: Phase transitions and the principle of detailed balance in living systems

Prof. Frederick C. MacKintosh (Physics & Astronomy, and the Center for Theoretical Biophysics, Rice University, Houston, TX USA)

The mechanics of cells and tissues are largely governed by scaffolds of filamentous proteins that make up the cytoskeleton, as well as extracellular matrices. Evidence is emerging that such networks can exhibit rich mechanical phase behavior. A classic example of a mechanical phase transition was identified by Maxwell for macroscopic engineering structures: networks of struts or springs exhibit a continuous, second-order phase transition at the isostatic point, where the number of constraints imposed by connectivity just equals the number of mechanical degrees of freedom. We will present recent theoretical predictions and experimental evidence for mechanical phase transitions in both synthetic and biopolymer networks. Living systems typically operate far from thermodynamic equilibrium, which affects both their dynamics and mechanical response. As a result of enzymatic activity at the molecular scale, living systems characteristically violate detailed balance, a fundamental principle of equilibrium statistical mechanics. We discuss fundamental non-equilibrium signatures of living systems, including violations of detailed balance at the meso-scale of whole cells.

Seminarroom 1+2
06 May 2019
04:30 PM

Colloquium: Interplay between superconductivity and non-Fermi liquid above a quantum critical point in a metal

Prof. Andrey Chubukov (University of Minnesota, USA)

I discuss the interplay between non-Fermi liquid behavior and superconductivity near a quantum-critical point (QCP) in a metal. It is widely thought that the tendency towards superconductivity and towards non-Fermi liquid behavior compete with each other, and if the pairing interaction is reduced below a certain threshold, the system displays a naked non-Fermi liquid QC behavior. I show that the situation is more complex. First, there is a difference between spin-triple and spin-singlet superconductivity. For spin-triplet pairing, thermal fluctuations are crucial and make superconducting transition first order. For spin-singlet pairing, they are essentially irrelevant, and the transition is second order. Second, I show that for spin-singlet pairing, there are multiple solutions with the same gap symmetry. For all solutions, except one, Tc vanishes when the pairing interaction drops below the threshold. For the one special solution, Tc remains finite even when the pairing interaction is arbitrary small, despite that there is no Cooper logarithm. I argue that superconductivity between this Tc and a lower T, when other solutions appear, is special, as it is entirely induced by fermions with the first Matsubara frequency. I show that this has specific implications for the observable quantities, such as the density of states and the spectral function.

Seminarroom 1+2+3
13 May 2019
04:30 PM

Colloquium: Many-body optical excitations in solid-state systems

Prof. Dr. Atac Imamoglu (ETH Zürich, Institute of Quantum Electronics, Schweiz)

Two dimensional materials provide new avenues for synthesizing compound quantum systems. Monolayers with vastly different electric, magnetic or optical properties can be combined in van der Waals heterostructures which ensure the emergence of new functionalities; arguably, the most spectacular example to date is the observation of strong correlations and low electron density superconductivity in Moire superlattices obtained by stacking two monolayers with a finite twist angle. Optically active monolayers such as molybdenum diselenide provide a different "twist" as they allow for investigation of nonequilibrium dynamics in van der Waals heterostructures by means of femtosecond pump-probe measurements. Moreover, interactions between electrons and the elementary optical excitations such as excitons or polaritons, provide an ideal platform for investigation of quantum impurity physics, with possibilities to probe both Fermi- and Bose-polaron physics as well as mixtures with tunable density of degenerate fermions and bosons. After introducing the framework we use to describe many-body optical excitations in van der Waals heterostructures, I will describe two recent developments in the field. The first experiment uses pump-probe measurements to demonstrate how exciton-electron interactions beyond the non-self-consistent T-matrix approximation lead to optical gain by stimulated cooling of exciton-polaron-polaritons. The second experiment shows that a tri-layer system, consisting of two semiconducting monolayers separated by an insulating layer, could lead to hybridization of intra- and inter-layer excitons. The latter has potential applications ranging from strongly interacting polaritons to reaching Feshbach resonance condition in exciton-electron scattering.

Seminarroom 1+2
20 May 2019
04:30 PM

Colloquium: Axial fields in phonic crystals

Prof. Dr. Sebastian Huber (ETH Zürich, Dept. Theoretische Physik, Schweiz)

The elastic properties of materials are determined by a few material constants such as the Young’s modulus. Using super-structures one can effectively change these “constants”. In this way we obtain functionalities such as wave-guiding, acoustic lensing or programmable failure. I will show how topological band theory, known from the description of electrons in solids, provides us with a powerful design-principle for such mechanical metamaterials. Moreover, mechanical metamaterials offer a powerful platform for the study of fundamentally new phenomena that are hard to observe in other arenas. Here, I will highlight the first measurement of a quadrupole topological insulator in a silicon based metamaterial and the implementation of an axial gauge field in an acoustic Weyl system.

Seminarroom 1+2
27 May 2019
04:30 PM

Colloquium: Quantum Memories

Prof. Dr. Georgi Dvali (LMU München / New York Univ.)

In this talk I introduce a phenomenon of enhancement of quantum memory storage capacity that is taking place in a wide class of systems with high occupancy of cold bosons at criticality. The S-matrix formulation shows that black holes are prominent members of this category. From particle physicists perspective a black hole is describable as a critical state of maximal memory storage capacity of soft gravitons at an extremely high occupation number. The same is true about a de Sitter type Universe. Both systems carry a maximal amount of quantum information that is protected against the standard semi-classical evolution. This leads to some important consequences. In particular, the primordial quantum memory pattern carried by the de Sitter Hubble patch from which our Universe evolved as a result of cosmic inflation was not erased by the latter process and is of observational importance. This opens up a conceptually new opportunity of catching the glimpses of the Universes's primordial quantum hair. The universal nature of the enhanced memory phenomenon allows to study and simulate black hole and de Sitter type quantum information storage and processing in laboratory systems with cold bosons.

Seminarroom 1+2
03 Jun 2019
04:30 PM

Colloquium: Programming Shape

Prof. Lakshminarayanan Mahadevan (Harvard University, USA)

Shape constrains and enables function across scales. But how can we design and control shape, i.e. solve the basic inverse problems in physical geometry. I will discuss our work in this area that focuses on 3 different paradigms: (i) using origami to fold flat sheets into curved surfaces, (ii) using kirigami to reshape planar domains and tile arbitrary surfaces, (iii) using biomimetic 3D and 4D printing combined with designer metrics that allow us to “grow” a flat surface into a complex 3D shape such as a flower or a face.

Seminarroom 1+2
17 Jun 2019
04:30 PM

Colloquium: The formalism of open quantum systems and its application to quantum metrology

Prof. Susana F. Huelga (Ulm University)

The description of open quantum systems is amenable to a broad range of theoretical tools. Those include the derivation of different types of reduced master equations from specific microscopic modes and under the validity of physically motivated assumptions. A conceptually different approach relies on the formulation of phenomenological master equations, which in the more abstract formalism yield to the description of open system dynamics in terms of quantum channels. Using quantum metrology as a thread, I will illustrate the interrelation and complementarity of different formalisms to describe open quantum systems in order to provide a comprehensive approach to determining fundamental limits to the ultimate achievable precision in metrology and sensing.

Seminarroom 1+2
24 Jun 2019
04:30 PM

Colloquium: Biological photonics

Prof. Pete Vukusic (University of Exeter)

The study of structural colour in brightly coloured animals is an exciting interdisciplinary area of research. Complex photonic bandgap (PBG) structures that occur naturally cross a broad range of animals and plants, suggest broad innovation both in nature’s use of materials and in its manipulation of light and colour. In certain butterflies for instance, ultra-long-range visibility of up to one half-mile is attributed to photonic structures that are formed by discrete multilayers of cuticle and air. This contrasts, in other butterfly species, to photonic structures designed more for crypsis and which not only produce strong polarisation effects but can also create additive colour mixing using highly adapted periodicity. Optical systems also exist that employ remarkable 2D and 3D photonic crystals of cuticle to produce partial PBGs, with the effect that bright colour is reflected, or fluorescence emission is inhibited, over specific angle ranges. From the perspective of modern optical technology, these structures arguably indicate a significant functional advance, since in principle, such 2D and 3D periodicities are potentially able to manipulate the flow of light more completely. This presentation will offer an overview, for a more general audience, of this emerging field of study, as well as describing several of the exciting recent discoveries that reflect nature’s optical design ingenuity, and some technological applications to which they are currently being applied.

Seminarroom 1+2
01 Jul 2019
04:30 PM

Colloquium: Quantum Atom Optics: Ocean & Universality in Quantum Dynamics

Prof. Dr. Markus Oberthaler (Universität Heidelberg, Kirchhoff-Institut für Physik)

The experimental platform of atoms manipulated by light offers answers to a broad spectrum of open questions. With two explicit and very different examples I will give you a glimpse how broad this spectrum is. I will start with a fundamental question in oceanography: At what time has the deep water in the ocean been in exchange with the atmosphere? Quantum atom optics offers the experimental possibility to detect the very rare Argon 39 atoms one by one and with that allows the dating of water samples as small as ten liters [1]. A very different question in physics is about the existence of universal behavior. Specifically in respect to time dynamics this has only recently been discussed theoretically in the context of the early phase of a heavy ion collision. 'Universal' means in this context, that the evolution does not depend on the initial condition and follows the scaling hypothesis in time and space. I will introduce the concept and present the first observation of this phenomenon in highly controlled ultracold Bose gases [2]. [1] Ar-39 dating with small samples provides new key constraints on ocean ventilation, Nature Comm. 9, 5046 (2018). [2] Observation of universal dynamics in a spinor Bose gas far from equilibrium, Nature 563, 217 (2018).

Seminarroom 1+2
08 Jul 2019
04:30 PM

Colloquium: Exploiting the Malleability of Disorder to Design Biologically-Inspired Function

Prof. Andrea J. Liu (University of Pennsylvania, USA)

Physicists have been thinking for a century about ordered solids. But ordered systems can’t compete with what biological systems such as proteins, which aren’t ordered, can do. We’ve discovered that relaxing the constraint of order increases design flexibility enormously, so that systems can be tuned to perform complex biologically-inspired tasks. Allostery in a protein is a phenomenon in which a molecule binding locally to one site affects the ability of another molecule to bind at a second distant site. Inspired by the long-range coupled conformational changes that constitute allosteric function in proteins, we tune in “allostery” into disordered mechanical networks derived from granular packings by modifying the network architecture to control the local strain at one point in such a network in response to a strain applied elsewhere in the system. In another biological example, the vascular network in the brain contracts and dilates blood vessels in order to direct enhanced blood flow to multiple specific regions of the brain as it performs multiple tasks at once. We have designed flow networks to accomplish similar complex tasks. In both examples, we address a key question: what, precisely, are we tuning into the structure in order to accomplish the function? Surprisingly, we find that the structure/function relationship is not geometrical, but topological in nature.

Seminarroom 1+2
15 Jul 2019
04:30 PM

Colloquium: Topological Magnetic Order far from Equilibrium

Prof. Dr. Christian Pfleiderer (Technische Universität München)

Topological spin textures in chiral magnets such as skyrmions attract great interest as a possible route towards spintronics devices. Central to the suitability for applications are the mechanisms controlling the long-term stability and decay processes. Starting from the spectrum of low-lying excitations the effects of kinetic arrest and supercooling will be compared with strongly driven non-equilibrium dynamics. These identify topological magnetic order far from equilibrium as an exciting approach for the exploration of the fundamentals of topological protection and in the search for dynamically stabilized electronic phases.

Seminarroom 1+2
22 Jul 2019
04:30 PM

Colloquium: Light-matter-life interactions at the micron scale

Prof. Thomas E. Mallouk (Pennsylvania State University, USA)

In 1676, using candle light for illumination and a small glass sphere as the lens, Antonie van Leeuwenhoek revealed to the world the beauty and complexity of a microscopic universe densely populated by living microorganisms. Today, using lasers, spatial light modulators, digital cameras and computers, we investigate the statistical and fluid mechanics of microswimmers in ways that were unimaginable only 50 years ago. With light we can image bacteria as they swim rapidly through 3D environments, apply gentle and controllable force fields or sculpt the 3D structure of their environment. In addition to shaping the physical world outside cells we can also use light to control the internal biological state of microorganisms that are genetically engineered to respond to light signals. I will review our recent work on the interactions between light, matter and bacteria, from the fundamental problems of rectification and non-equilibrium steady states in active matter to the use of genetically modified bacteria as propellers for micro-machines or as a "living" paint that can be controlled by light.

Seminarroom 1+2
29 Jul 2019
04:30 PM

Colloquium: Quantum Materials: Full of Frustration and Correlations

Prof. Dr. Martin Dressel (Universität Stuttgart)

The pioneering work on geometrical frustration dates back to the 1920s, when Linus Pauling realized that the hydrogen bonds between H$_2$O molecules in ice can be allocated in multiple ways. A given oxygen atom in water ice is situated at the vertex of a diamond lattice and has four nearest-neighbor oxygen atoms, each connected via an intermediate proton according to the ice rule “two-in two-out”. Although these considerations used electric dipoles, Phil Anderson mapped them to a spin model possessing an extensive degeneracy of states. Quantum spin liquids attract great interest due to their exceptional magnetic properties characterized by the absence of long-range order down to low temperatures despite the strong magnetic interaction. Commonly these compounds are strongly correlated electrons systems, and their electrodynamic response is governed by the Mott gap in the excitation spectrum. Here we will summarize and discuss the optical properties of several two-dimensional quantum spin liquid candidates with different degrees of effective correlations. Placing organic molecules on a triangular lattice, a spin liquid ground state can be realized which allows us to investigate the genuine Mott state in the absence of magnetic order. Combining our optical data with pressure-dependent transport studies and theoretical calculations, we can construct a universal phase diagram of the correlation-controlled Mott insulator. But how important is the coupling of the fluctuating magnetic moments? How important is disorder for the electronic properties? If this resembles a quantum phase transition, is there a superconducting phase found in the vicinity and what is the superconducting glue? Can our findings be generalized, when going to a kagome or hexagonal lattice, realized in Herbert-smithites or $\alpha$-RuCl$_3$ for instance? Reference: A. Pustogow et al., Nature Materials 17, 773 (2018); Phys. Rev. Lett. 121, 056402 (2018). M. Dressel et al., J. Phys. Cond. Matter 30, 203001 (2018)

Seminarroom 1+2
05 Aug 2019
04:30 PM

Colloquium: Critical and incoherent electron systems and superconductivity within the Sachdev-Ye-Kitaev approach

Prof. Jörg Schmalian (Institut für Theorie der Kondensierten Materie (TKM), Karlsruhe)

The established and highly successful description of metals is based on Landau’s Fermi liquid theory. The relevant phase space for electron-electron collisions is determined by the Pauli blocking of a degenerate Fermi gas due to its Fermi surface. In some strongly correlated systems narrow bands form and the energetics of the system at elevated energies or temperatures becomes dominated by strong interactions and is no longer restricted by Fermi-surface phase-space effects. To develop a well-controlled approach of this regime is an important question in the theory of strongly correlated electrons. In this talk I will give an overview over the description of incoherent and critical electronic systems using the Sachdev-Ye-Kitaev approach. We consider versions of the model where electrons interact with each other, with boson collective modes, and even with phonons. We also comment on the very direct relation to holographic approaches to strongly coupled quantum theories. Finally we address the emergence of superconductivity in such an incoherent metal and show that pairing and superconductivity of a fully incoherent electronic system is allowed and leads to a pairing state with high transition temperature but low condensation energy.

Seminarroom 1+2+3
12 Aug 2019
04:30 PM

Colloquium: From single-cell variability and correlations across lineages to the population growth

Prof. Ariel Amir (Harvard University, John A. Paulson School, USA)

Genetically identical microbial cells often display diverse phenotypes. Stochasticity at the single-cell level contributes significantly to this phenotypic variability, and cells utilize a variety of mechanisms to regulate noise. In turn, these control mechanisms lead to correlations in various cellular traits across the lineage tree. I will present recent models we developed for understanding cellular homeostasis, with special focus on protein levels and cell size. These models allow us to characterize single-cell variability, including the emerging correlations and distributions. I will discuss the implications of stochasticity on the population growth. In contrast to the dogma, we find that variability may be detrimental to the population growth, suggesting that evolution would tend to suppress it.

Seminarroom 1+2
26 Aug 2019
04:30 PM

Special dynamics of water pearls

Prof. David Quéré (ESPCI & Ecole polytechnique)

A few tricks (hydrophobic texture, Leidenfrost state, etc.) allow us to keep water drops with a spherical shape, which induces spectacular properties. We describe a few of them. We also challenge the water mobility in the cases where it is expected to be impeded - for instance by reducing the drop size or by increasing the water temperature.

Seminarroom 1+2
16 Sep 2019
04:30 PM

Colloquium: New Phases of Quantum Magnets in and out of Equilibrium

Prof. Dr. Christian Rüegg (Paul Scherrer Institute, Villigen, Schweiz)

In quantum magnets spins form well-defined lattices and serve as model systems to study many-body quantum phases such as interacting quantum-dimer qubits, spin Luttinger-liquids, Bose glasses, or magnon Bose-Einstein condensates. Neutron, muon and photon sources are unique tools for high-precision studies of such phases, and of their correlations and excitations in as well as out of equilibrium. An overview of current frontiers in the field will be presented with special focus on recent developments in computational physics and exciting new opportunities that free electron lasers like SwissFEL and European XFEL will offer to study the time-dependence and out-of-equilibrium quantum mechanics of such systems.

Seminarroom 1+2+3
30 Sep 2019
04:30 PM

Colloquium: Topology and scale invariance in atomic Flatland

Prof. Jean Dalibard (College de France, Laboratoire Kastler Brossel, Paris, France)

In a 2D world, most transitions towards ordered states of matter like crystals or magnets would not occur because of the increased role of fluctuations. However, non-conventional topological transitions can still occur, as understood by Kosterlitz and Thouless (2016 Nobel prize). In this talk I will present some important features of Flatland physics explored with cold atomic gases, and connect them with other prominent topological properties of matter, such as quantum-Hall type phenomena.

Seminarroom 1+2
07 Oct 2019
04:30 PM

Colloquium: Using Machine Learning for Prediction of Large, Complex, Spatially Extended Systems

Prof. Edward Ott (University of Maryland, USA)

We first review the basic idea of using machine learning in conjunction with a limited duration of time series data to construct a closed-loop, autonomous, dynamical system that can predict the future evolution of the state of the unknown system that generated the data [1]. Using the reservoir computing type of machine learning, we then present examples of extensions and applications of this idea. These will include a parallel implementation enabling forecasting of the states of very large spatiotemporally chaotic systems with local interactions [2], a hybrid scheme where an imperfect knowledge-based model component is combined with a limited-size machine learning component to achieve prediction performance much better than that of either of the components acting alone [3], an architecture combining the parallel and hybrid schemes, and generalization of ensemble Kalman filtering to cyclic prediction using the parallel/hybrid machine learning schemes. As an example of the potential utility of these elements for large complex spatiotemporally chaotic systems, their use in our ongoing project on improving weather forecasting [4] will be outlined. [1] Jaeger, Haas, Science (2004). [2] Pathak, Hunt, Girvan, Lu, Ott, Phys Rev Lett (2018). [3] Pathak, Wikner, Fussell, Chandra, Hunt, Girvan. Ott, CHAOS (2018). [4] Collaborators on our current weather forecasting project: T. Acomano, M. Girvan, B. Hunt, G. Katz, J. Reggia, I. Szunyogh, C.-Y. Wang, A. Wikner.

Seminarroom 1+2
21 Oct 2019
04:30 PM

Colloquium: Fluid flows shaping morphology

Dr. Karen Alim (Max Planck Institute for Dynamics and Self-Organization Goettingen; Technische Universität in München)

Fluid flows can induce long-ranged interactions and propagate information on large scales. Especially during the development of an organism, coordination on large scales is essential. What are the principal mechanisms of how fluid flows induce, transmit and respond to biological signals and thus control morphology? Fluid flows are particularly prominent during the growth and adaptation of transport networks. Here, the network-forming slime mold Physarum polycephalum emerged as a model system. Investigating the pivotal role of fluid flows in this live transport network we find that flows are patterned in a peristaltic wave across the network thereby optimizing transport. In fact, flows are hijacked by signals to propagate throughout the network. This simple mechanism is sufficient to explain surprisingly complex dynamics of the organism like scaling of peristaltic wave with network size and finding the shortest path through a maze.

Seminarroom 1+2
28 Oct 2019
04:30 PM

Colloquium: Making Quantum Matter from Light

Prof. Jonathan Simon (Chicago University, USA)

In this talk I will discuss ongoing efforts at UChicago to explore matter made of light. I will begin with a broad introduction to the challenges associated with making matter from photons, focusing specifically on (1) how to trap photons and imbue them with mass and charge; (2) how to induce photons to collide with one another; and (3) how to drive photons to order, by cooling or otherwise. I will then provide as examples two state-of-the-art photonic quantum matter platforms: microwave photons coupled to superconducting resonators and transmon qubits, and optical photons trapped in multimode optical cavities and made to interact through Rydberg-dressing. In each case I will describe a synthetic material created in that platform: a Mott insulator of microwave photons, stabilized by coupling to an engineered, non-Markovian reservoir, and a Laughlin molecule of optical photons prepared by scattering photons through the optical cavity. Indeed, building materials photon-by-photon will provide us with a unique opportunity to learn what all of the above words mean, and why they are important for quantum-materials science. Finally, I will conclude with my view of the broad prospects of photonic matter in particular, and of synthetic matter more generally.

Seminarroom 1+2
25 Nov 2019
04:30 PM

Colloquium: Topological Physics in HgTe based Quantum Devices

Prof. Dr. Laurens W. Molenkamp (Physikalisches Institut (EP3), Würzburg University, Würzburg, Germany)

Topological insulators are a novel class of materials that exhibit a novel state of matter – while the inside (bulk) of the materials is electrically insulating, their surface is metallic. This effect occurs because the band structure of the materials is topologically different (in a mathematical sense) from the outside world. This talk describes our discovery of this type of behavior while studying the charge transport properties of thin, two-dimensional layers of the narrow-gap semiconductor HgTe. These layers exhibit the quantum spin Hall effect, a quantized conductance which occurs when the bulk of the material is insulating. Using various tricks one can show that the transport occurs along one-dimensional, spin-polarized channels at the edges of the sample. Also thicker HgTe samples can be turned into topological insulators, but now the surface states are two-dimensional metallic sheets. The metal in these sheets is rather exotic in that the band structure is similar to that encountered for elementary particles – the charge is carried by so-called Dirac fermions. This means that experiments on these layers can be used to test certain predictions from particle theory that are difficult to access otherwise. As an example, I will describe experiments where a supercurrent is induced in the surface states by contacting these structures with Nb electrodes. AC investigations indicate that the induced superconductivity is strongly influenced by the Dirac nature of the surface states. We present strong evidence for the presence of a gapless Andreev mode in our junctions. Finally, by playing with the strain in the layers, we can turn HgTe into a Dirac semimetal, which exhibits the ‘axial anomaly’ known from particle physics when the Fermi level is tuned to the Dirac points.

Seminarroom 1+2
22 Jan 2018
04:30 PM

Colloquium: The long way to steady state fusion plasmas - the superconducting stellarator device Wendelstein 7-X

Prof. Thomas Klinger (MPI fuer Plasmaphysik, Greifswald)

The stable generation of high temperature Hydrogen plasmas (ion and electron temperature in the range 10-20 keV) is the basis for the use of nuclear fusion to generate heat and thereby electric power. The most promising path is to use strong, toroidal, twisted magnetic fields to confine the electrically charged plasma particles in order to avoid heat losses to the cold, solid wall elements. Two magnetic confinement concepts have been proven to be most suitable: (a) the tokamak and (b) the stellarator. The stellarator creates the magnetic field by external coils only, the tokamak by combining the externally created field with the magnetic field generated by a strong current in the plasma. “Wendelstein 7-X” is the name of a large superconducting stellarator that goes into operation after 15 years of construction. With 30 $m^3$ plasma volume, 3 T magnetic field on axis, and 10 MW micro wave heating power, Hydrogen plasmas are generated that allow one to establish a scientific basis for the extrapolation to a future fusion power plant. It is a unique feature of Wendelstein 7-X to be able to operate high-power Hydrogen plasmas under steady-state conditions, more specifically for 1800 s (note that the world standard is now in the 10 s ballpark). This talk provides a review of the principles of nuclear fusion and discusses the key physics subjects of optimized stellarators. The sometimes adventurous undertaking to construct such a first-of-a-kind device is summarized as well as the most important findings during the first operation phase of Wendelstein 7-X. We finish with an outlook towards the fusion power station and address the most important remaining issues to be addressed in the framework of the world-wide fusion research endeavor.

Seminarroom 1+2+3
07 Feb 2018
04:30 PM

Gutzwiller Colloquium: Two-dimensional melting: New algorithms, new insights

Werner Krauth (Laboratoire de Physique Statistique, Ecole Normale Sup rieure, Paris, and Director of Research at the CNRS, France)

The hard-disk model has exerted outstanding influence on computational physics and statistical mechanics. Decades ago, hard disks were the first system to be studied by reversible Markov-chain Monte Carlo methods satisfying the detailed-balance condition and by molecular dynamics. It was in hard disks, through numerical simulations, that a two-dimensional melting transition was first seen to occur even though homogeneous short-range interacting particle systems cannot develop crystalline order. Analysis of the system was made difficult by the absence of powerful simulation methods. In recent years, we have developed a class of irreversible event-chain Monte Carlo algorithms that violate detailed balance. They realize thermodynamic equilibrium as a steady state with non-vanishing probability flows. A new factorized Metropolis filter turns them into a paradigm for general Monte Carlo calculations. I will in particular show how the event-chain Monte Carlo algorithm has allowed us to demonstrate that hard disks melt with a first-order transition from the liquid to the hexatic and a continuous transition from the hexatic to the solid. Event-chain computations have also lead to our new understanding of two-dimensional melting for soft disks, that has been intensely studied in experiment. Finally, I will discuss two-dimensional melting on a substrate (as it is realized in skyrmion systems), and for active particles, and will present a very recent application of the event-chain algorithm to Coulomb-type long-range-interacting systems.

Seminarroom 1+2+3
26 Feb 2018
04:30 PM

Colloquium: Chern numbers counted in a synthetic-dimension quantum Hall strip

Prof. Ian Spielman (University of Maryland, USA)

Ultra cold atoms are remarkable systems with a truly unprecedented level of experimental control and one application of this control is creating topological band structures. The most natural approach centers on creating suitable real-space lattice potentials that the atoms experience. Here we present our experimental work which uses the internal atomic states as an additional ``synthetic'' dimension. We engineered a two-dimensional magnetic lattice in an elongated strip geometry, with effective per-plaquette flux about 4/3 times the flux quanta. The long direction of this strip is formed from a 1D optical lattice while the short direction is built from the 5 mF states comprising the f=2 ground state hyperfine manifold of Rb-87. We imaged the localized edge and bulk states of atomic Bose-Einstein condensates in this strip, with single lattice-site resolution along the narrow direction. In this 5-site wide strip we are able to delineate between bulk behavior quantified by Chern numbers and edge behavior which is not.

Seminarroom 1+2+3
05 Mar 2018
04:30 PM

Colloquium: The Quantum Way of Doing Computations

Prof. Dr. Rainer Blatt (Institute for Experimental Physics, University of Innsbruck and Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Austria)

Since the mid-nineties of the 20th century, it became apparent that one of the centuries’ most important technological inventions, computers in general and many of their applications could possibly be further enhanced by using operations based on quantum physics. This is timely since the classical roadmap for the development of computational devices, commonly known as Moore’s law, will cease to be applicable within the next decade. This is due to the ever-smaller sizes of the electronic components that will enter the realm of quantum physics. Computations, whether they happen in our heads or with any computational device, always rely on real physical devices and processes. Data input, data representation in a memory, data manipulation using algorithms and finally, data output require physical realizations with devices and practical procedures. Building a quantum computer then requires the implementation of quantum bits (qubits) as storage sites for quantum information, quantum registers and quantum gates for data handling and processing as well as the development of quantum algorithms. In this talk, the basic functional principle of a quantum computer will be reviewed. It will be shown how strings of trapped ions can be used to build a quantum information processor and how basic computations can be performed using quantum techniques. In particular, the quantum way of doing computations will be illustrated with analog and digital quantum simulations, which range from the simulation of quantum many-body spin systems over open quantum systems to the quantum simulation of a lattice gauge theory.

Seminarroom 1+2+3
19 Mar 2018
04:30 PM

Colloquium: Statistical Mechanics, Localization and Periodically Driven Quantum Systems

Shivaji Sondhi (Princeton University)

The statistical mechanics of equilibrium systems is characterized by two fundamental ideas: that closed systems approach a late time thermal state and that of phase structure wherein such late time states exhibit singular changes as various parameters characterizing the system are changed. Recent progress has established generalizations of these ideas which apply to periodically driven, or Floquet, closed quantum systems. I will describe this progress, which centrally uses other recent advances in our understanding of many body localization. I will describe how it has resulted in the discovery of entirely new phases such as the Pi-spin glass/Floquet time crystal which exist only in driven quantum systems.

Seminarroom 1+2
26 Mar 2018
04:30 PM

Colloquium: Lasing to Photon Bose-Einstein-Condensation Crossover: Open versus Closed System Dynamics

Prof. Dr. Martin Weitz (Universität Bonn)

Bose-Einstein condensation has been observed with cold atomic gases, exciton-polaritons, and more recently with photons in a dye-solution filled optical microcavity. I will here describe measurements of my Bonn group observing the transition between usual lasing dynamics and photon Bose-Einstein condensation. The photon Bose-Einstein condensate is generated in a wavelength-sized optical cavity, where the small mirror spacing imprints a low-frequency cutoff and photons confined in the resonator thermalize to room temperature by absorption re-emission processes on the dye molecules. This allows for a particle-number conserving thermalization, with photons showing a thermodynamic phase transition to a macroscopically occupied ground state, the Bose-Einstein condensate. When the thermalization by absorption and re-emission is faster than the photon loss rate in the cavity, the photons accumulate at lower energy states above the cavity cutoff, and the system finally thermalizes to a Bose-Einstein condensate of photons. On the other hand, for a small reabsorption with respect to the photon loss, the state remains laser-like. I will also report recent measurements of the heat capacity of the photon gas, which were performed under the conditions of the thermalization being much faster than both photon loss and pumping. At the Bose-Einstein phase transition, the observed specific heat shows a cusp-like singularity, as in the $\lambda$-transition of liquid helium, illustrating critical behavior of the photon gas. In my talk, I will begin with a general introduction and give an account of current work and future plans of the Bonn photon gas experiment.

Seminarroom 1+2+3
09 Apr 2018
04:30 PM

Colloquium: Engineering and Visualizing Majoranas in Chains and Hinges

Prof. Ali Yazdani (Princeton University, USA)

A variety of one-dimensional electronic systems can be engineered to host topological superconductivity and Majorana zero modes. In this talk, I’ll describe experiments on two different one-dimensional platforms. One is based on chains of magnetic atoms the work on which grew out of early efforts on the study of localized Bogoliubov quasi-particles near individual magnetic atoms on a superconductors. We have now performed a series of experiments to establish the presence of Majorana’s in this system, including a recent study of their spin polarization. A second system is based on introducing superconductivity on the hinge states of a high order topological insulator. Using combination of magnetism and superconductivity, we are exploring how Majorana zero mode can emerge in this system.

Seminarroom 1+2+3
16 Apr 2018
04:30 PM

Colloquium: Molecular motors interacting with actin filaments

Prof. Jean-François Joanny (Institut Curie, PSL University, Paris)

Actin filaments are the essential components of the cytoskeleton that provide the elasticity of a cell. In a cell they interact with many proteins and in particular molecular motors. This talk will present 3 biological situations where actin filaments interact with molecular motors in relation with important cellular functions : the control of actin polymerization, intracellular transport and cell migration. Actin filaments are treadmilling : they grow at one end and depolymerize at the other end. The first example of interaction between actin and molecular motors deals with the induced depolymerization of actin filaments by myosin1b molecular motors studied in motility assays. The depolymerization requires a catch bond motor with a detachment rate decreasing strongly when the motor is under force Molecular motors navigate the cytoskeleton to position vesicles and organelles at specific locations in the cell. In order to understand this transport process, the group of Pascal Martin at Institut Curie has used an antiparallel network of overlapping filaments. Beads coated with myosin motors accumulate at the midline of the pattern. The accumulation is well described by a three-state model of bead transport, in which active beads locally sense the net polarity of the filament network by frequently detaching from and reattaching to the filaments. The migration of immune cells is guided by several chemical signals, but also by physical cues such as the hydraulic resistance of the vessels in which they travel. This barotaxis effect has been studied in vitro by the groups of M. Piel and A.M. Lenon using microfluidic channels. We show that barotaxis results from a force imbalance at the scale of the cell, amplified at the scale of a network of vessels.

Seminarroom 1+2+3
23 Apr 2018
04:30 PM

Colloquium: Transitions and transients in complex spatio-temporal dynamics of the heart

Prof. Dr. Ulrich Parlitz (MPI f. Dynamik und Selbstorganisation)

Electro-mechanical excitation waves in the heart may exhibit different spatio-temporal dynamics ranging from repeated plane waves to scroll waves or spatio-temporal chaos, resulting in life threatening arrhythmias. This kind of chaotic dynamics in excitable cardiac media is often characterised by significant complexity fluctuations (including laminar phases) and can be non-persistent exhibiting supertransients, with lifetimes of the chaotic phases increasing exponentially with the system size. Terminating or at least shortening chaotic transients can be life saving in the medical context of cardiac arrhythmias. Therefore, we study the impact of perturbations on the duration of transients and features of the terminal phase of chaotic transients. Practically, such perturbations can be applied via so-called virtual electrodes where electrical heterogeneities of the cardiac muscle act as local excitation sites when subjected to a global electric field. In the talk we shall present novel results on the nonlinear dynamics of the heart including features of the terminal phase of transient chaos, parameter and state estimation, as well as experimental studies and modalities.

Seminarroom 1+2+3
07 May 2018
04:30 PM

Colloquium: Stochastic thermodynamics: From principles to the cost of precision

Prof. Dr. Udo Seifert (Universität Stuttgart)

For the macroscopic world, classical thermodynamics formulates the laws governing the transformation of various forms of energy into each other. Stochastic thermodynamics extends these concepts to micro- and nano-systems embedded or coupled to a heat bath where fluctuations play a dominant role. Examples are colloidal particles in time-dependent laser traps, single biomolecules manipulated by optical tweezers or AFM tips, and transport through quantum dots. For these systems, exact non-equilibrium relations like the Jarzynski relation, fluctuation theorems and, most recently, a thermodynamic uncertainty relation have been discovered. First, I will introduce the main principles and show a few representative experimental applications. In the second part, I will discuss the universal trade-off between the thermodynamic cost and the precision of any biomolecular, or, more generally, of any stationary non-equilibrium process. By applying this thermodynamic uncertainty relation to molecular motors, I will introduce the emerging field of "thermodynamic inference" where relations from stochastic thermodynamics are used to infer otherwise yet inaccessible properties of (bio)physical and (bio)chemical systems.

Seminarroom 1+2+3
14 May 2018
04:30 PM

Colloquium: Hybrid active matter: when particles and living cells play together

Francoise Brochard (Curie Institute, Paris, France)

We introduce the broad field of active matter, a novel class of non-equilibrium materials composed of many interacting units that individually consume energy and collectively generate motion or mechanical stresses. Unlike swarms of fish and flocks of birds, cells or ants can support static loads because cells are bound by transient links. This leads to the concept of “entangled active matter” , which emerged recently to provide a unified understanding of the behavior of swarms of adhesive particles ranging from vibrating staples, to ants, and to cellular aggregates [1]. Recently we have focused on cellular aggregate – nanoparticles hybrid systems. This system is of great interest as it has been previously shown that particles can modify the mechanical properties of cells in terms of adhesion area, proliferation and motility. We study both small particles (up to few microns), which are digested by cells by endocytosis and phagocytosis, and larger particles, which do not enter in the cells, leading to a completely different physics. Nanostickers (size 20 nm ) [2] We show that nanoparticles, within a limited size range, can be used as a glue “nanostickers”to enable the formation of self-assembled aggregates by promoting cell–cell interactions. We model the cell-cell adhesion induced by the nanostickers using a three states dynamical model where the NPs are free, adsorbed on the membrane or internalized by endocytosis. We find that carboxylated polystyrene NPs are more efficient than the silica NPs of the same size, which were reported to induce fast wound healing and to glue soft tissue by Leibler et al. Nanostickers by increasing the cohesion of tissues and tumors may have important applications for cellular therapy and cancer treatment. Microparticles ( size 1micron): gluttonous cells[3]. We study the spreading of cell aggregates deposited on adhesive substrates decorated with microparticles. A cell monolayer expands around the aggregate. The cells at the periphery uptake the microparticles by phagocytosis, clearing the substrate and forming an aureole of cells full of particles. We study the dynamics of spreading, the width of the aureole, and the level of cell internalization as a function of the size, nature and density of the beads. The radius and width of the aureole allow quantification of the MP volume fraction incorporated by the cell, leading to an easy, fast, and inexpensive cell – particle internalization measurement. Macroparticles ( size 2-20 microns) ”Activated Brownian motion” Performing the same experiment with particles which are too big to be eaten, we observed that they are put into motion by the cells.We also describe also the mechanical properties of hybrid particles-cells aggregates (surface tension, elastic modulus, viscosity) using pipette aspiration technique [4], the phase separation between dead and living matter and how they spread . [1] F Brochard-Wyart et al, Entangled Active Matter: from ants to living cells EPJE 2015 [2] B.Brunel et al Nanostickers for cells: a model study using cell–nanoparticle hybrid aggregates Soft Matter 12 (38), 7902-7907. 2015 [3] Grégory Beaune^1 et al *5,6How gluttonous cell aggregates clear substrates coated with microparticles, Scientific Reports 7, Article number: 15729 (Nov 2017).[4] David Gonzalez-Rodriguez et al. Soft Matter Models of developing Tissues and Tumors. Science 338, 910; 1226418 (2012)

Seminarroom 1+2+3
11 Jun 2018
04:30 PM

Colloquium: Weather and climate: Deterministic or stochastic?

Prof. Michael Ghil (Ecole Normale Supérieure, Paris and University of California, Los Angeles)

The atmosphere, ocean, and other components of the climate system behave in a fairly irregular way. A major surprise of the late 20th century was the realization that such behavior could be produced by natural systems with a small number of degrees of freedom, governed by fully deterministic, but nonlinear laws. Still, the climate system has a large number of degrees of freedom, and ample room for random factors to intervene. Can we reconcile a low-order, deterministically nonlinear description of weather or climate with a high-order, possibly linear but random one? This talk will present some steps on the road to such a "grand unification," and implications for climate variability, sensitivity and predictability will be discussed. References: 1. Ghil, M., 2002: Natural climate variability, in Encyclopedia of Global Environmental Change, T. Munn (Ed.), Vol. 1, J. Wiley & Sons, Chichester/New York, pp. 544–549. 2. Ghil, M., 2014: Climate variability: Nonlinear and random aspects, in Encyclopedia of Atmospheric Sciences, 2nd edn., G. R. North, J. Pyle and F. Zhang (Eds.), Elsevier, vol. 2, pp. 38–46. 3. Ghil, M., 2017: The wind-driven ocean circulation: Applying dynamical systems theory to a climate problem, Discr. Cont. Dyn. Syst. – A, 37(1), 189–228, doi:10.3934/dcds.2017008.

Seminarroom 1+2+3
18 Jun 2018
04:30 PM

Colloquium: Tensor Network Machine Learning Models

Dr. Edwin Miles Stoudenmire (Flatiron Institute, Center for Computational Quantum Physics, New York, USA)

Tensor networks are an efficient representation of interesting many-body wavefunctions and underpin powerful algorithms for strongly correlated systems. But tensor networks could be applied much more broadly than just for representing wavefunctions. Large tensors similar to wavefunctions appear naturally in certain families of models studied extensively in machine learning. Decomposing the model parameters as a tensor network leads to interesting algorithms for training models on real-world data which scale better than existing approaches. In addition to training models directly for recognizing labeled data, tensor network real-space renormalization approaches can be used to extract statistically significant "features" for subsequent learning tasks. I will also highlight other benefits of the tensor network approach such as the flexibility to blend different approaches and to interpret trained models.

Seminarroom 1+2+3
25 Jun 2018
04:30 PM

Colloquium: Neural-Network Quantum States: from Condensed Matter to Quantum Computing

Prof. Giuseppe Carleo (Simons Foundation, Flatiron Institute, New York, USA)

Seminarroom 1+2+3
02 Jul 2018
04:30 PM

Once Upon a Time in Kamchatka - The Extraordinary Search for Natural Quasicrystals

Paul J. Steinhardt (Princeton University, New Jersey, USA)

Abstract: Quasicrystals are exotic materials with symmetries that were once thought to be impossible for matter. The first known examples were synthesized in the laboratory over 35 years ago, but could Nature have beaten us to the punch? This talk will describe the search that took over a dozen years to answer this question, resulting in one of the strangest scientific stories you are ever likely to hear.

Seminarroom 1+2
23 Jul 2018
04:30 PM

Colloquium: Dark matter challenges of the solid state

Prof. Piers Coleman (Center for Materials Theory, Dept Physics and Astronomy, Rutgers University, NJ 08854, USA)

At the turn of the 20th century, physicists faced an uncanny range of unsolved problems: simple questions, such as why hot objects change color, why matter is hard and why the sun keeps on shining, went unanswered. These problems heralded a new era of quantum physics. What was truly remarkable about discovery in this heroic era, was the intertwined nature of research in the lab and in the cosmos: solving superconductivity really did help answer why the sun keeps on shining, while looking at the stars provided clues as to why matter is hard. The challenges facing us today, epitomized by our failure to quantize gravity and the mysteries of dark matter and energy, are not just problems facing particle physics and astronomy, but problems that challenge physics to its core. What is perhaps less well known, is that physics in the lab and cosmos are just as intertwined today, as they were a hundred years ago. I will talk today about the less well-known dark matter challenges of the solid state, epitomized by the strange metals with linear resistivity that accompany high temperature superconductivity, the recent discovery of insulators with Fermi surfaces and quantum criticality - the solid-state version of a black hole in the phase diagram. The solution of these laboratory-scale problems fundamentally challenge our understanding of emergent quantum matter, and they are no less intertwined with their cosmological counterparts than they were a hundred years ago. I will highlight three Dark-Matter challenges that have arisen in heavy fermion physics[1-4], emphasizing their connections with other strongly correlated quantum materials and discussing some of our recent theoretical efforts to make progress on them: quantum criticality, hidden order and the possibility of new classes of broken symmetry outside the Hartree-Fock/BCS paradigm and topology [5]. [1] Piers Coleman, “Heavy Fermions and the Kondo Lattice, a 21st Century Perspective”, arXiv:1509.05769 (2015). [2] Joe Thompson and Zachary Fisk, “Progress in Heavy Fermion Superconductivity: Ce115 and other materials”, J. Phys. Soc. Jpn. 81, 011002 (2012). [3] Philipp Gegenwart, Qimiao Si and Frank Steglich, ”Quantum criticality in heavy-fermion metals”,Nature Physics 4, 186 - 197 (2008). [4] Maxim Dzero et al, “Topological Kondo Insulators”, arXiv 1506.05635, Ann. Rev. Cond. Matt. Phys., Volume 7:249-280 (2016). [5] B. S. Tan et. al, “Unconventional Fermi surface in an insulating state”, Science 349, 287-290 (2015).

Seminarroom 1+2
13 Aug 2018
04:30 PM

Colloquium: Optical thermodynamics of highly multimode systems

Prof. Demetrios Christodoulides (University of Central Florida, Orlando)

The prospect of judiciously utilizing both optical gain and loss has been recently suggested as a means to control the flow of light. This proposition makes use of some newly developed concepts based on non-Hermiticity and parity-time (PT) symmetry-ideas first conceived within quantum field theories. By harnessing such notions, recent works indicate that novel synthetic structures and devices with counter-intuitive properties can be realized, potentially enabling new possibilities in the field of optics and integrated photonics. Non-Hermitian degeneracies, also known as exceptional points (EPs), have also emerged as a new paradigm for engineering the response of optical systems. In this talk, we provide an overview of recent developments in this newly emerging field. The use of other type symmetries in photonics will be also discussed.

Seminarroom 1+2
27 Aug 2018
04:30 PM

Colloquium: The Brief But Fascinating History of Silicon Spin Chains

Dr. Steven Erwin (Naval Research Laboratory Center for Computational Materials Science, Washington, USA)

Thirty years ago, scientists first observed that when a small amount of gold is deposited on the surface of silicon, both the gold and silicon atoms automatically organize themselves into parallel linear rows, so-called "atom chains", with nearly perfect structural order. This observation marked the beginning of a new research direction in which theoretical predictions about "physics in one dimension" could now be investigated experimentally using the standard tools of surface science such as scanning tunneling microscopy, x-ray diffraction, and photoemission. A particularly striking discovery, first reported ten years ago, was that at low temperature the silicon chains can develop local magnetic moments, which form regular highly ordered, periodic patterns. These "silicon spin chains" have now become the main focus of this research field. This talk will describe three recent theoretical and experimental aspects of silicon spin chains: the possibility of magnetic ordering in these one-dimensional systems; the prospects for using surface chemistry to tailor spin chains by creating or destroying individual spins; and the properties and dynamics of solitons in the spin chains.

Seminarroom 1+2+3
10 Sep 2018
04:30 PM

Colloquium: Thermodynamics of superconducting quantum circuits

Prof. Jukka Pekola (Low Temperature Laboratory, Department of Applied Physics, Aalto University School of Science, AALTO, Finland)

Thermodynamics of superconducting quantum circuits Superconducting circuits provide a platform for stochastic thermodynamics experiments in both classical and quantum regimes (“circuit Quantum Thermodynamics”). I first review the ideas, principles and examples of classical experiments utilizing single electron charge as the stochastic variable. I present experiments over the past several years on classical fluctuation relations and Maxwell Demons (MD), the latter in form of both non-autonomous Szilard Engines and autonomous MDs. Recent highlights on entropy reduction and rare events will be reviewed. In the second part of the talk I focus on open quantum systems formed of superconducting qubits and resonators, coupled to heat baths. In this context microwave photons carry the heat between the system and bath. I present experiments on quantum heat transport mediated by a transmon qubit, progress on superconducting quantum heat engines and refrigerators, and on detecting single microwave photon quanta. Success in the last item would allow us to perform true stochastic thermodynamics experiments in the quantum regime, and to realize quantum MDs.

Seminarroom 1+2
24 Sep 2018
04:30 PM

Colloquium: Probing many-body localization using ultracold atoms

Prof. Immanuel Bloch (Max-Planck-Institut fuer Quantenoptik, Garching)

A fundamental assumption in statistical physics is that generic closed quantum many-body systems thermalise under their own dynamics. Recently, the emergence of many-body localised (MBL) systems has questioned this concept, challenging our understanding of the connection between statistical physics and quantum mechanics. In my talk, I will report on several recent experiments carried out in our group on the observation of Many-Body Localisation in different scenarios, ranging from 1D fermionic quantum gas mixtures in driven and undriven Aubry-André type disorder potentials and 2D systems of interacting bosons in 2D random potentials. It is shown that the memory of the system on its initial non-equilibrium state can serve as a useful indicator for a non-ergodic, MBL phase. Furthermore, I will present new results on the slow relaxation dynamics in the ergodic phase below the MBL transition and experiments that explore the resilience of a 2D MBL phase when coupled to a finite thermal bath. Our experiments represent a demonstration and in-depth characterisation of many-body localisation, often in regimes not accessible with state-of-the-art simulations on classical computers.

Seminarroom 1+2+3
15 Oct 2018
04:30 PM

Colloquium: Exploration in Reinforcement Learning

Prof. Ron Meir (Technion, Haifa, Israel)

In Reinforcement Learning an agent learns how to act in an environment in order to achieve desired goals. In general, the agent only has access to partial information from the world, and has to learn how to act appropriately in face of this uncertainty. One of the earliest results in the theory of Optimal Control (Feldbaum 1965) demonstrates that in order to act appropriately, the agent must also probe the environment in order to gain information and reduce uncertainty. In other words, exploring the environment is an essential component of learning to act. However, very few provably effective procedures were proposed in the control literature to solve this problem. In recent years, several elegant solutions to the problem of exploration have been proposed in the Machine Learning literature for the case of finite state and action spaces (which was of little concern to the control theorists). However, the problem of effective exploration in continuous spaces is still very much open, and of increasing importance in many applications. We survey some recent approaches to exploration in continuous domains, in both model based and model free settings, and suggest open problems for future research.

Seminarroom 1+2
22 Oct 2018
04:30 PM

Colloquium: On Growth and Form of Microorganisms on Liquid Substrates

Prof. David R. Nelson (Lyman Laboratory, Harvard University, USA)

The interplay between fluid flows and living organisms plays a major role in the competition and organization of microbial populations in liquid environments. Hydrodynamic transport leads to the dispersion, segregation or clustering of biological organisms in a wide variety of settings. To explore such questions, we have created microbial range expansions in a laboratory setting by inoculating two identical strains of S. cerevisiae (Baker’s yeast) with different fluorescent labels on a nutrient-rich fluid 10^4 to 10^5 times more viscous than water. The yeast metabolism generates intense flow in the underlying fluid substrate several times larger than the unperturbed colony expansion speed. These flows dramatically impact colony morphology and genetic demixing, triggering in some circumstances a fingering instability that allows these organism to spread across an entire Petri dish in roughly 24 hours. We argue that yeast colonies create fluid flow by consuming nutrients from the surrounding fluid, decreasing the fluid’s density, and ultimately triggering a baroclinic instability when the fluid’s pressure and density contours are no longer parallel. Our results suggest that microbial range expansions on viscous fluids will provide rich opportunities to study the interplay between advection and spatial population genetics.

Seminarroom 1+2
29 Oct 2018
04:30 PM

Colloquium: Active field theories: Statistical physics and the arrow of life

Prof. Michael Cates (University of Cambridge, DAMTP, UK)

Active matter comprises particles whose microscopic dynamics breaks time-reversal symmetry (TRS) via the continuous conversion of fuel into motion, resulting in entropy production at the microscopic scale. Examples include bacteria and synthetic self-propelled colloids. Equilibrium statistical physics concepts, for instance the Boltzmann distribution, are not applicable to active matter because these concepts assume the TRS of the underlying microscopic laws. When viewed at a coarse grained level, the microscopic absence of TRS may either remain obvious at large scales or become almost undetectable. In the latter case, we retain the hope that equilibrium concepts, at least in some modified form, may be applicable. This talk will discuss the conceptual toolbox needed to characterize the presence or absence of TRS at coarse-grained level, focusing on global and local measures of entropy production. Put differently: when, and how, can you tell whether life's movie is running backwards?

Seminarroom 1+2
05 Nov 2018
04:30 PM

Colloquium: An effective molecular orbital approach to electron phonon and pairing interactions in skipped valence and negative charge transfer gap Oxides

Prof. George A. Sawatzky (University of British Columbia Department of Physics & Astronomy, Vancouver, Canada)

In high oxidation state oxides like the trivalent Nickel oxides, tetravalent Co and Fe oxides as well as the parent superconductors BaBiO3 and SrBiO3 and High Tc hole doped cuprates, the cation electron affinity in the formal valence could end up larger than the O 2- ionization potential leading to a so called negative charge transfer gap. If the charge transfer energy is strongly negative, then we should really adopt starting electronic configurations such as Ni2+ rather than 3 + or Bi 3+ rather than 4+ with compensation holes in the O 2p valence band for charge neutrality. If in addition the lowest energy cation ionization states are strongly hybridized with the valence O 2p states the low energy scale electronic structure and be well described by a molecular orbital type of approach (1,2). This is a new approach to the Wannier function description (3) but with explicit inclusion of the O states which provides a natural path to inclusion of the electron phonon coupling, charge density wave formation, potential bipolaron formation and paring interactions in superconductors. We discuss recent developments in this approach and show that the effective electron phonon coupling involving these molecular like orbitals is much stronger than that estimated from density function approaches. We also show that this leads to Peierls like charge density wave like ground states and we describe how the electron phonon coupling involving the hopping integrals rather than the on-site energies evolves into a large effective attractive interaction between low energy scale electrons. I will also briefly describe how these effects lead to our coelution that the ion battery material LiNiO2 should be viewed as an “entropy-stabilized charge- and bond-disproportionated glass”.

Seminarroom 1+2+3
12 Nov 2018
04:30 PM

Colloquium: Quantum Optomechanics: exploring mechanical motion in the quantum regime

Markus Aspelmeyer (Universität Wien, Österreich)

The quantum optical control of solid-state mechanical devices, quantum optomechanics, has emerged as a new frontier of light-matter interactions. Devices currently under investigation cover a mass range of more than 17 orders of magnitude - from nanomechanical waveguides of some picograms to macroscopic, kilogram-weight mirrors of gravitational wave detectors. This development has been enabled by the insight that quantum optics provides a powerful toolbox to generate, manipulate and detect quantum states of mechanical motion, in particular by coupling the mechanics to an optical or microwave cavity field. Originally, such cavity optomechanical systems have been studied from the early 1970s on in the context of gravitational wave antennas. Advancements in micro-fabrication and micro-cavities, however, have resulted in the development of a completely new generation of nano- and micro-optomechanical devices. Today, 10 years after the first demonstrations of laser cooling of micromechanical resonators, the quantum regime of nano- and micromechanical motion is firmly established. Recent experimental achievements include the generation of genuinely non-classical states of micromechanical motion such as quantum squeezing and entanglement. This level of control over solid-state mechanical degrees of freedom is now also being utilized in diverse application domains ranging from classical sensing, to low-noise optical coatings for precision interferometry, and also to photon-phonon quantum interfaces. From the fundamental physics point of view, one of the fascinating prospects of quantum optomechanics is to coherently control the motional degree of freedom of a massive object in an unprecedented parameter regime of large mass and long coherence time, hence opening up a new avenue for macroscopic quantum experiments. The availability of quantum superposition states involving increasingly massive objects could enable a completely new class of experiments, in which the source mass character of the quantum system starts to play a role. This addresses directly one of the outstanding questions at the interface between quantum physics and gravity, namely “how does a quantum system gravitate?”.

Seminarroom 1+2
03 Dec 2018
04:30 PM

Colloquium: Quantum optics using atomic arrays

Professor Darrick Chang (ICFO - The Institute of Photonic Sciences, Castelldefels, Spain)

Ensembles of atoms or other quantum emitters are envisioned to be an important component of quantum applications, ranging from quantum memories for light to photon-photon gates to metrology. It has historically been an outstanding challenge to exactly solve for the quantum dynamics of an optical field as it propagates through and interacts with an ensemble. The standard axiomatic approach is to use the one-dimensional Maxwell-Bloch equations, which treats the interaction between the ensemble and a quasi-1D optical mode of interest, while the interaction with the remaining 3D continuum of modes is assumed to result in independent spontaneous emission of excited atoms. Strictly speaking, this assumption cannot be correct, as the emission of light is a wave phenomenon, and thus the emitted intensity must depend on interference and correlations between the atoms. Here, we discuss an alternative theoretical approach, which accounts for interference and the precise atomic positions. In this formalism, an interacting quantum spin model describes the dynamics of the atomic internal degrees of freedom under multiple photon scattering, while the field properties can subsequently be re-constructed from the spin correlations. Using this model, we then show how interference can be exploited as an extremely powerful resource to suppress the unwanted emission of light and the subsequent loss of information into undesirable directions. The effects of interference are particularly prominent in ordered arrays of emitters. As two specific examples, we construct a new protocol for a quantum memory for light based upon an ordered array, whose error rate as a function of system resources scales exponentially better than previously known bounds. We also show the interrogation time in an optical lattice clock can be significantly extended, through the excitation of collective subradiant atomic states whose spontaneous emission rates are strongly suppressed. These results raise the intriguing question of whether interference can be used to broadly re-define the performance limits of all applications involving atomic light-matter interfaces.

Seminarroom 1+2
06 Feb 2017
04:30 PM

Colloquium: The Amplitude Mode in Condensed Matter : Higgs Hunting on a Budget

Daniel Arovas (Univesity of California, San Diego)

Seminarroom 1+2+3
13 Feb 2017
04:30 PM

Transport and other related electronic properties in model lattice structures

Antonietta de Sio (Carl von Ossietzky University Oldenburg)

Ultrafast and nano-optics: Watching the motion of electrons in nanostructures

Seminarroom 1+2+3
27 Feb 2017
04:30 PM

Soft X-ray shines on the new attosecond horizon through the water window

Prof. Zenghu Chang (University of Central Florida, Orlando)

Seminarroom 1+2+3
27 Mar 2017
04:30 PM

Magnons, spinons, Majorana fermions and quantum spin liquids

Prof. Stephen Nagler (Oak Ridge National Laboratory)

In recent years many physicists researching quantum materials have become very excited about an unusual state of matter: the quantum spin liquid (QSL). In this talk I will explore the difference between “conventional” ordered magnetic systems and QSLs. To understand these systems the way physicists do one needs to appreciate the importance of collective elementary excitations. In ordinary magnets these are called spin-waves, or, in the quantum version, magnons. These will be explained and discussed along with other excitations that are important in quantum magnetism sometime called “triplons” and spinons. I will discuss a major technique for characterizing these excitations: inelastic neutron scattering. The last part of the talk will examine one material of particular recent interest: $\alpha-RuCl_3$. This material orders magnetically, but it is close to a special kind of quantum spin liquid called the “Kitaev quantum spin liquid”, and exhibits unusual excitations that might be related to particles known as Majorana Fermions. Finally, I will discuss how the magnetic order can be suppressed by either site-dilution of the magnetic $Ru^{3+}$ ions, or the application of a magnetic field. The resultant consequences on the magnetic excitation spectrum are seen to be of particular interest.

Seminarroom 1+2+3
03 Apr 2017
04:30 PM

Topological sound and odd viscosity in chiral active matter

Prof. Vincenzo Vitelli (Leiden University)

Abstract: Active materials are composed of interacting particles individually powered by motors. In this talk, we focus on chiral active materials that violate parity and time reversal symmetry. First, we show how to generate topological sound in fluids of self-propelled particles exhibiting a spontaneous chiral active flow under confinement. These topological sound modes propagate unidirectionally, without backscattering, along either sample edges or domain walls and despite overdamped particle dynamics. Next, we discuss an exotic transport coefficient characteristic of quantum Hall fluids, called odd viscosity, which controls the hydrodynamics of classical fluids composed of active rotors. This odd viscosity couples pressure to vorticity leading to transverse flow in piston compression experiments. We envision that such transverse response may be exploited to design self-assembled hydraulic cranks that convert between linear and rotational motion in microscopic machines powered by active rotors fluids.

Seminarroom 1+2+3
08 May 2017
04:30 PM

Topological Photonics and Topological Insulator Lasers

Prof. Mordechai Segev (Technion - Israel Institute of Technology, Haifa, Israel)

Seminarroom 1+2+3
22 May 2017
04:30 PM

Martin Gutzwiller-Fellowship Award Ceremony: Unusual few-body quantum states and their many-body implications

Prof. Dr. Chris Greene (Purdue University, USA)

Simple systems with only 3 or 4 interacting particles can behave in a bizarre, counter-intuitive manner. Examples to be discussed in this Colloquium include ultra-long-range Rydberg molecules with enormous electric dipole moments, as well as states of a few neutral particles that resonantly form a cluster. Moreover, insights from a few-body viewpoint can help to understand some of the rich many-body systems being actively explored, from the unitary Bose gas to the fermionic or bosonic flavors of the fractional quantum Hall effect.

Seminarroom 1+2
29 May 2017
04:30 PM

Cotranscriptional Folding of RNA Nanostructures and Devices

Prof. Ebbe Sloth Andersen (Aarhus University, Denmark)

RNA nanotechnology has the great potential to allow us to produce well-defined nanostructures and devices inside cells and thus open up a wide range of design opportunities in synthetic biology. To achieve this goal we need to understand the design principles of geometry, folding kinetics and topology that will allow us to genetically encode well-defined RNA nanostructures that self-assemble during the transcription process. We have recently introduced the single-stranded RNA origami method and validated the architecture by transcribing RNA tiles that assemble into lattices of different geometries. I will introduce new software tools that allow interactive design of RNA origami structures using a library of functional modules and new sequence design approaches that allow large structures to be designed. Also I will show our latest progress in developing larger three-dimensional RNA origami structures and functional RNA nanodevices with applications in biosensing and diagnostics.

Seminarroom 1+2+3
19 Jun 2017
04:30 PM

The multi-scale structure and dynamics of macaque visual cortex at cellular and synaptic resolution

Prof. Markus Diesmann (Forschungszentrum Jülich)

Seminarroom 1+2+3
17 Jul 2017
04:30 PM

El Nino as a Topological Insulator: A Surprising Connection Between Climate, and Quantum, Physics

Professor Brad Marston (Brown University, Providence, USA)

Symmetries and topology play central roles in our understanding of physics. Topology explains the precise quantization of the Hall effect and the protection of surface states in topological insulators against scattering from disorder or bumps. However discrete symmetries and topology have so far played little role in thinking about the fluid dynamics of oceans and atmospheres. I show that, as a consequence of the rotation of the Earth that breaks time reversal symmetry, equatorially trapped Kelvin and Yanai waves emerge as topologically protected edge modes. Thus the oceans and atmosphere of Earth naturally share basic physics with topological insulators. As equatorially trapped Kelvin waves in the Pacific ocean are an important component of El Nino Southern Oscillation, these new results demonstrate that topology plays a surprising role in Earth’s climate system.

Seminarroom 1+2+3
24 Jul 2017
04:30 PM

Localization: Moving beyond Statistical Mechanics

Christopher Laumann (Boston University)

The central assumption of statistical mechanics is that interactions between particles establish local equilibrium. Isolated quantum systems, however, need not equilibrate; this happens, for example, when sufficient quenched disorder causes localization. The many-body localized (MBL) phase transports neither heat nor charge; may possess orders disallowed in equilibrium; and, may exhibit quantum coherence even when highly excited. In this talk, I will review the emerging understanding of how quantum localization can lead to new quantum phenomena even in highly excited states. I will give some theoretical intuition about how this might be used to build a better quantum computer and also review some of the latest experiments investigating localization.

Seminarroom 1+2+3
25 Sep 2017
04:30 PM

Quantum Metrology, the art of parameter estimation

Anna Sanpera Trigueros, ICREA and Universitat Autònoma Barcelona, Spain

Seminarroom 1+2+3
16 Oct 2017
04:30 PM

Gutzwiller Colloquium: Making Living Matter from the bottom up

Ramin Golestanian (University of Oxford)

There are many ways to study life, and one that is particularly appealing to physicists is regarding it as self-organized active soft matter that is away from equilibrium ``just the right way’’. In this Colloquium, I will discuss this notion, and provide a number of examples of how we can begin to put together simple systems - from basic ingredients that we fully understand - that would exhibit the kind of active behaviour we find in living systems. I will address the question of stability of a living system made of active components and propose a fundamentally new mechanism in which a competition between chemical signalling and cell division can determine the homeostatic conditions at the systemic level.

Seminarroom 1+2+3
29 February 2016Satoru Nakatsuji
Uni Tokyo
"Novel quantum and functional phases in correlated electron systems: from spin liquids to anomalous Hall effect in chiral antiferromagnets"
14 March 2016

Eckart Meiburg

"Vorticity-based Models for Stratified Flows"
11 April 2016 Peter Lu
"Modern math in medieval islamic architecture"
25 April 2016Michael Ramsey
Uni Graz
"Photoemission Tomography: Why didn't we do this 30 years ago?"
09 May 2016Philipp Maass
Uni Osnabrueck
"Phase Transitions in Driven Lattice Gases and Brownian Motors"
23 May 2016Sublr Sachdev
"Quantum entanglement and the phases of matter"
20 June 2016Wilhelm Zwerger
Festkolloquium P. Fulde - Dresdner Physik Kolloq.
"High-temperature superconductivity below one microkelvin"
04 July 2016Roland Wiesendanger
Uni Hamburg
"Nanoscale skyrmions - A new twist for spintronics"
03 August 2016 Eric J. Heller

"Shedding light on condensed matter"
15 August 2016Eckhard Schöll
TU Berlin
"Chimera states in complex networks"
29 August 2016Eberhard Bodenschatz
MPI for Dynamics and Self-Organization
"Ciliated surfaces and transport networks"
12 September 2016David Landau
University of Georgia
"Replica exchange Wnag-Landau sampling: a new paradigm for petascale Monte Carlo simulation"
10 October 2016 James A. Yorke
University of Maryland
"The Many Facets of Chaos"
17 October 2016Andrew Oates
University College London
"Period and Patter in the Embryo"
28 November 2016Louis DiMauro
Columbus, Ohio
"Strong-field probing of atomic and molecular dynamics"
26 January 2015Henk Stoof
University Utrecht
"The sound of light"
20 April 2015Jürgen Meyer-ter-Vehn
MPI für Quantenoptik,  Garching
18 May 2015Jané Kondev
Brandeis University, Waltham, USA
"Chromosome Folding in Cells"
11 May 2015Ragnar Fleischmann
MPI for Dynamics and Self-Organization Göttingen
"Waves in Random Media: Branched Flows and the Statistics of Extreme Waves"
08 June 2015

Peter Young
University of California Santa Cruz

Martin Gutzwiller Fellowship, Award Ceremony
"Mind the gap: solving optimization problems on a quantum computer"
15 June 2015Tomas Vicsek
Eötvös University, Budapest
"Quantitative approaches to hierarchy"
22 June 2015Carlo Beenakker
Universität Leiden
"Chaotic scattering of Majorana fermions: complexity without complex numbers"
29 June 2015Michel Devoret
Yale University
"Implementing cat-codes in Josephson quantum circuits"
06 July 2015Alex Arenas, Universitat Rovira i Virgili, Tarragona & MasonA.Porter, University of Oxford "Introduction to Multilayer Networks"
13 July 2015Dirk van der Marel
University of Geneva
"Optical detection of magnetic and electric phase-transitions in Rare-Earth Nickelates"
27 July 2015Michael Rosenblum
Potsdam University
"The Kuramoto model and its extensions: synchronization transition, partial synchrony, and chimeras"
24 August 2015 Alexander Govorov
Ohio University
"Physics of bio-assembled nanostructures: chirality, Fano effect and hot plasmonic electrons"
31 August 2015Randy Hulet "Many-body Physics with Ultracold Atomic Gases"
14 September 2015Charles Marcus
Niels Bohr Institute, University of Copenhagen
"The status of experiments to detect and control Majorana modes in Condensed Matter systems, towards the long-term goal of topological quantum computing"
28 September 2015Hidenori Takagi
MPI für Festkörperforschung Stuttgart
"Exotic electronic states produced by strong spin-orbit coupling in complex Ir oxide"
12 October 2015Joachim Krug
Universität Köln
"How predictable is evolution?"
03 February 2014Sergei Turitsyn
School of Engineering and Applied Science, Aston University
"Optical wave turbulence in fibre lasers"
24 March 2014JochenMannhart
Max Planck Institute for Solid State Research, Stuttgart
"Oxide Interfaces - A Fantastic World for Electrons; From MOSFETs to Novel Electron Systems"
17 March 2014Sergey M. Bezrukov
NICHD, National Institutes of Health, Bethesda, MD
"Entropy potentials in description of biological channels and other confining structures"
06 May 2014
Hiroshi Sugiyama
Kyoto University
"Single-Molecule Observation in the DNA Origami Nanostructures"
19 May 2014 Luciano Pietronero
Universita' di Roma Sapienza
"New Metrics for Economic Complexity: Measuring the Intangible Growth Potential of Countries"
26 May 2014David L. Andrews
University of East Anglia, Norwich
"Photon Wave Fronts: Frontiers in Photonics"
16 June 2014Klaus Lehnertz
Universität Bonn
"Large-scale epileptic networks"
21 July 2014Steve Simon
University of Oxford
"Topological Matter and Why You Should Be Interested"
01 September 2014Federico Becca
SISSA - International School for Advanced Studies
"Gapless and gapped spin liquids in Heisenberg models"
22 September 2014Rodolfo Jalabert
IPCMS, Université de Strasbourg
"Loschmidt echo in complex systems"
06 October 2014James S. Schilling
Washington University
"Contrasting Effects of Extreme Pressure on Highly Correlated Electron Behavior"
17 November 2014 Jean-Luc Lehners
Max-Planck-Institute for Gravitational Physics, Albert-Einstein-Institute, Potsdam-Golm
"Before the Big Bang"
24 November 2014Frank Stienkemeier
Universität Freiburg
"Real-time excitation and ionization dynamics in clusters"
28 January 2013 Claudio Castelnovo
University of Cambridge
"Dynamics of fractionalised particles in condensed matter physics"
21 January 2013 Gene Myers
MPI of Molecular Cell Biology and Genetics, Dresden
"Building Cellular Models with Light Microscopy"
04 February 2013 Ivo F. Sbalzarini
Center of Systems Biology, MPI of Molecular Cell Biology and Genetics, Dresden
"Particle Methods for Computational Systems Biology"
11 February 2013 Peter Grassberger
University of Calgary, Canada
"The many faces of percolation"
18 February 2013Howard Stone
Princeton University
"Wetting and drying of fibers "
15 April 2013Erez Hasman
Technion - Israel Inst. of Technology
"Spinoptical metamaterials: spin-controlled photonics"
22 April 2013 Ralf Metzler
Universität Potsdam
"Ergodicity Violation and Ageing in anomalous Diffusion"
13 May 2013Thomas Elsaesser
Max-Born-Institut, Berlin
"Ultrafast structural dynamics in ionic crystals mapped by femtosecond x-ray powder diffraction"
27 May 2013Tsuneyoshi NakayamaMartin Gutzwiller Fellowship, Award Ceremony
"Complex Disordered Systems: from Quantum Glass till Thermoelectric Clathrates"
17 June 2013Jacques Laskar
IMCCE, Observatoire de Paris
"Frequency Map Analysis. Application to stability analysis of the solar system and particle accelerators."
08 July 2013Matthias Weidemüller
Universität Heidelberg
"Dressing Photons with Rydberg Atoms"
01 July 2013 Ed Grant
University of British Columbia
"Penning Lattice: Dissociation and the development of spatial correlation in a molecular ultracold plasma"
22 July 2013Achim Rosch
Universität Köln
"Skyrmions and monopoles in chiral magnets"
19 August 2013Heinz-Peter Breuer
Universität Freiburg
09 September 2013Mathias Fink
ESPCI ParisTech, Langevin Institute
"Controlling waves at subwavelength scales in space and time through complex media"
16 September 2013Moty Heiblum
Weizmann Institute of Science
"Controlled dephasing in mesoscopic systems"
23 September 2013Naoto Nagaosa
RIKEN, Wako, Japan
"Topological particle in magnets – Skyrmion –"
30 September 2013 Hermann Haken
Universität Stuttgart
"Reminiscences on the early days of synergetics"
07 October 2013 Andreas Burkert
Ludwig Maximilians University, Munich
"Watching the Little Gas Cloud G2 on its Way into the Galactic Supermassive Black Hole"
14 October 2013Stefano Ruffo
Università di Firenze
"Models with interactions that weakly decay with distance"
11 November 2013Vahid Sandoghdar
Max Planck Institute for the Science of Light, Erlangen
"On efficient interaction of photons and atoms: from quantum optics to biophotonics"
18 November 2013 Roland Wiesendanger
Universität Hamburg
"Complex Spin States in Nanostructures"
25 November 2013 Albert Stolow
National Research Council, Canada
"Dynamics of Polyatomic Molecules in Laser Fields"
02 December 2013 Andrew Huxley
Edinburgh University
"Superconductivity and modulated states close to ferromagnet quantum critical points"
12 December 2013 David A. Weitz
Harvard University
"Fluctuations and stiffness of cells"
13 February 2012 Andrew G. Green
London Centre of Nanotechnology
"New Horizons in Quantum Criticality"
26 March 2012 Arthur Voter
Los Alamos National Laboratory
"Recent Advances in Accelerated Molecular Dynamics Methods"
19 March 2012 Roger Guimera
Universitat Rovira i Virgili, Tarragona
"Statistical inference for the discovery of hidden interactions in complex networks"
02 April 2012Yoshinori Tokura
The University of Tokyo
"Emergent electromagnetic phenomena from topological spin textures"
16 April 2012Luis Silva
Instituto de Plasmas e Fusão Nuclear Complexo Interdisciplinar, Lisbon
"Intense lasers in plasmas: from accelerators to relativistic shocks"
23 April 2012 Holger Stark
TU Berlin
"Active motion in the microscopic world: From swinging and tumbling to bacterial locomotion"
21 May 2012 Hidenori Takagi
RIKEN, Japan
"Emergent phases of correlated electrons in transition metal oxides"
14 May 2012 Albert-László Barabási
Northeastern University, Boston
"Network Science: From Structure to Control"
18 June 2012 Joaquim Pinto
Universität zu Köln
"Extreme events, climate change and related impacts"
25 June 2012Hari C. Manoharan
Department of Physics, Stanford University
"Molecular Graphene"
02 July 2012Boris AltshulerMartin Gutzwiller Fellowship, Award Ceremony
"Anderson Localization – looking forward."
09 July 2012 Dmitri Talapin
The University of Chicago
"The evolution of nanomaterials - From fundamental science to practical applications"
16 July 2012Ruth Nussinov
Center for Cancer Research, Frederick, USA
"Networks in the Cell: Structural networks of signaling pathways on the proteome scale"

30 July 2012

Gil Refael
"Messy magnets and dirty superfluids"
13 August 2012Phil Hodgkin
The Walter and Eliza Hall Institute of Medical Research
Ken Duffy
National University of Ireland
"Reverse engineering the immune system"
08 October 2012Steve Gervin
Yale University
"Quantum Measurements and Back-Action (Spooky and Otherwise)"
29  October 2012Tomas Bohr
Technical University of Denmark
"Spontaneous Symmetry Breaking on Fluid Surfaces"
12 November 2012 F. Duncan M. Haldane
Princeton University
"Entanglement, Topology and Geometry in the Fractional Quantum Hall Fluid"
19 November 2012Constantino Tsallis
Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro
"Nonadditive entropy and applications in natural, artificial and social complex systems"
26 November 2012 Robin Santra
CFEL Hamburg
"Ultrafast x-ray atomic physics"
10 December 2012 Marc Timme
MPI Göttingen
"Braess Paradox, (In-)Stability and Optimal Design: Network Dynamics of Modern Power Grids"
14 February 2011 Harald Engel
TU Berlin
"Wave nucleation in excitable media"
21 February 2011 Klaus Kroy
Universität Leipzig
"Hot Brownian Motion"
28 February 2011 Ali Yazdani
Princeton University
"Helical Metals on the Surfaces of Topological Insulators"
21 March 2011 Ben Simons
Cambridge University
"Universalities of stem cell fate in adult tissues"
28 March 2011 Victor Gurarie
University of Colorado
"Non-Abelian particles in a two dimensional world"
04 April 2011Andreas Radbruch
Deutsches Rheuma-Forschungszentrum, Berlin
"Modelling and experimentation: Approaching the complexity of the immune system"
11 April 2011Peter Jung
Ohio University
"How nerves get into shape"
18 April 2011 Qimiao Si
Rice University
"Quantum Criticality and Emergent Phases"
02 May 2011 Ulrike Feudel
Carl von Ossietzky Universität Oldenburg
"Patterns in the ocean resulting from the interplay between hydrodynamics and biology"
09 May 2011 Fred Wolf
Max-Planck-Institut für Dynamik und Selbstorganisation
"The self-organization and quantitative universality in the evolution of the visual corte"
16 May 2011 Chandra Varma
University of California, Riverside
"What determined T_c in Superconductors through Pairing by Electronic Fluctuations"
06 June 2011Piers Coleman
Rutgers University
"Magnetism and Superconductivity: A new era of convergence in condensed matter physics."
20 June 2011Wolfgang Schleich
Universität Ulm
"The linearity of quantum mechanics and the birth of the Schroedinger equation"
27 June 2011 Cristián Huepe
Unaffiliated Research Scientist, Chicago
"Dynamics of collective motion: from toy models to experiments"
04 July 2011 Felix von Oppen
FU Berlin
"Making and manipulating Majorana fermions for topological quantum computation"
11 July 2011 Satya Majumdar
Université Paris-Sud
"The Wonderful World of Brownian Functionals"
01 August 2011Joseph Klafter
Tel Aviv University
"How strange is strange kinetics"
12 September 2011Igor Aronson
Argonne National Laboratory
"Active Magnetic Colloids: From Self-Assembled Swimmers to Simple Robots"
10 October 2011Herschel Rabitz
Princeton University
"Control of phenomena in the sciences over vast length and time scales "
24 October 2011Albert Fert
Unité Mixte de Physique CNRS/Thales
"Graphene, carbon nanotubes and spintronics "
07 November 2011Alfred R. Osborne
Università degli Studi di Torino
"Rogue Waves and Holes in  the Sea"
21 November 2011Robert Moshammer
MPI für Kernphysik Heidelberg
"Time-Resolved Experiments with Atoms and Molecules using XUV and IR Laser Pulses" 
16 December 2011Ioannis Kevrekidis Martin Gutzwiller Fellowship, Award Ceremony
"Equation-Free and Variable-Free: a computer-assisted approach to modeling complex systems"
11 January 2010 Werner Krauth
Ecole Normale Supérieure, Laboratoire de Physique Statistique, Paris
"'Perfect' sampling: a new paradigm for Monte Carlo calculations in statistical physics"
25 January 2010 Eugenia Kalnay
University of Maryland
"Use of breeding to find the physical causes of instabilities"
01 March 2010 Hao Tjeng
Max Planck Institute for Chemical Physics of Solids, Dresden
"Electron spectroscopy on 3d^1 transition-metal oxides: model studies for testing new theoretical approaches"
08 March 2010Maria Carmen Romano
University of Aberdeen
"Traffic dynamics of translation: modelling the synthesis of proteins"
15 March 2010 Hans von Storch
Institute for Coastal Research, GKSS Research Center, Geesthacht
"Utility of Climate Models"
29 March 2010Kirill Shtengel
University of California, Riverside
"Non-Abelian anyons: New particles for less than a billion"
12 April 2010 Erwin Frey
Ludwig-Maximilians-Universität München
"Bacterial Games: on the role of space and stochasticity in coevolutionary dynamics"
26 April 2010Klaus Mecke
Universität Erlangen-Nürnberg
"Minkowski Tensors: linking physics and geometry of materials"
03 May 2010 Ulrich Schollwöck
Ludwig-Maximilians-Universität München
"Playing with Superlattices: Ultracold Atoms out of Equilibrium"
10 May 2010Günther Hasinger
Max-Planck-Institut für Plasmaphysik
"The way to a fusion power station"
25 May 2010 Gertrud Zwicknagl
TU Braunschweig
"The f-electron's 'double life'"
31 May 2010Martin van Hecke
Universiteit Leiden
"Flow of Foams from a Jamming Perspective"
07 June 2010Philip Kim
Columbia University
"Relativistic quantum physics at the tip of your pencil: pseudo spins in graphene"
14 June 2010Ian Affleck
University of British Columbia
"The Kondo screening cloud: what it is and how to observe it"

21 June 2010

Paul Fendley
University of Virginia
"From Few to Many"
28 June 2010Florin Diacu
University of Victoria
"Collision and near-collision dynamics in various n-body problems"
05 July 2010 Luca Peliti
Università di Napoli "Federico II"
"Fluctuation relations in physical biology"
12 July 2010Carlo Beenakker
Leiden University
"Majorana fermions in topological insulators"
26 July 2010 Götz S. Uhrig
Technische Universität Dortmund
"Coherent Control of Quantum Bits: Ideas against Decoherence"
09 August 2010Serge AubryMartin Gutzwiller Fellowship, Award Ceremony
"Different aspects of the localization of waves by  disorder, nonlinearity and else... a short review"
16 August 2010 Silke Ospelkaus
MPI für Quantenoptik
"Ultracold Polar Molecules - Ultracold Chemistry and Dipolar Collisions"
23 August 2010Subir Sachdev
Harvard University
"The phase diagrams of the high temperature superconductors"
30 August 2010Klaus Sengstock
Institut für Laser-Physik, Hamburg
"Ultracold Quantum Gases in Hexagonal Optical Lattices"
06 September 2010Gerald Gabrielse
Harvard University
"Fundamental Physics with Low Energy Particles of Antimatter and Matter"
13 September 2010 Sabine Sütterlin
Journalist in Residence
"What is it that journalists want from scientists?"
20 September 2010Kurt Kremer
MPI für Polymerforschung
"Multiscale Modelling of Soft Matter"
27 September 2010Michael Hastings
Medical Research Council, Laboratory of Molecular Biology
"Pacemaking and synchronisation in the brains circadian centre, the suprachiasmatic nucleus"
04 October 2010 Wieslaw Krolikowski
The Australian National University
"Nonlocal Solitons"
11 October 2010Mehran Kardar
Massachusetts Institute of Technology
"Manipulating Fluctuation-Induced Forces"
25 October 2010 Fabrizio Gabbiani
Baylor College of Medicine, Houston, TX
"Biophysics and Neural Computations Underlying Collision Avoidance Behaviors"
01 November 2010 Roland Ketzmerick
TU Dresden
"How fast can one tunnel into chaos?"
08 November 2010 Raymond Goldstein
University of Cambridge
"Microfluidics of Cytoplasmic Streaming"
22 November 2010 Reinhard Dörner
Universität Frankfurt am Main
"The Helium Dimer: Double ionization by photons"
29 November 2010 Jorge M. Pacheco
Universidade do Minho, Universidade de Lisboa
"Evolutionary dynamics of Climate Change under the Collective Risk Dilemma"
12 January 2009

Ulf Peschel
Universität Erlangen-Nürnberg

"Optics in curved space"
19 January 2009 Bruno Eckhardt
Universität Marburg
"Turbulence transition in pipe flow and other shear flows"
26 January 2009 Alexander Hartmann
Universität Oldenburg
"Simulation of rare events"
09 February 2009 David A. Weitz
Harvard University
"Mechanics of biopolymer networks"
23 February 2009 Royce K.P. Zia
Virginia Polytechnic Institute & State University
"Non-equilibrium statistical mechanics: A growing frontier
of "pure and applied" theoretical physics"
02 March 2009 Andrea Cavalleri
University of Hamburg
"Photo-control in complex solids"
09 March 2009 Walter Hofstetter
Universität Frankfurt
"Disorder and interaction in optical lattices"
16 March 2009 Thierry Giamarchi
University of Geneva
"Dirty bosons and cold atomic gases"
30 March2009 Andrei Varlamov
Università di Roma
"Giant Nernst effect due to fluctuating cooper pairs in superconductors"
06 April 2009 Olivier Pouliquen
Polytech Marseille
"Granular flows: From aerial to submarine avalanches"
20 April 2009Klaus Gerwert
Ruhr-Universität Bochum
"Proteins in action: Monitored by tr(time-resolved) FTIR spectroscopy"
27 April 2009Christoph Bruch
Max Planck Digital Library (MPDL)
"Will 'open access' change scientific publishing?"
04 May 2009 Yuriy A. Kosevich
Semov Inst. of Chemical Physics, Russian Academy of Sciences
"Bloch acceleration theorem and Bloch oscillations in complex electronic, acoustic and magnetic systems"
11 May 2009 Nadrian Seeman
New York University
"Using DNA information to control structure of matter in 3D"
18 May 2009 Jean Zinn-Justin
CEA Saclay
"Renormalization group approach to matrix models"
25 May 2009 Joshua Jortner
Tel Aviv University
"Economic Engineering"
15 June 2009Achim Wambach
Universitä:t zu Köln
"Adventures in the ultracold world"
08 June 2009 Marcus Anhäuser
Journalist in Residence 2009
"Science journalism: What is it all about?"
22 June 2009 Karl Friston
University College London
"Free-energy, perception and learning"
29 June 2009 Dieter Meschede
Universität Bonn
"Playing quantum marbles or can we make individual atoms interfere with each other?"
06 July 2009 Hans Peter Büchler
Universität Stuttgart
"Strongly correlated quantem phases with cold polar molecules"
15 July 2009 Michael Freedman
Microsoft Research
"Topology, physics and complexity: The birthing of the quantum computer"
20 July 2009 Alexander S. Mikhailov
Fritz-Haber-Institut der MPG, Berlin
"Nonlinear relaxation properties of elastic networks and nonequilibrium dynamics of protein machines"
03 August 2009Sergey A. Nikitov
Russian Academy of Sciences, Moscow
"Magnonic crystals and magnetic metamaterials based on magnetic films - New types of magnetic functional materials: Overview and perspectives"
07 September 2009 Gerhard G. Paulus
Universität Jena
"Recent experiments in above-threshold ionization"
14 September 2009 Eric J. Heller
Harvard University
"Tunneling and Coherence in Few and Many Body Systems"
21 September 2009Juan M. R. ParrondoMartin Gutzwiller Fellowship, Award Ceremony
"Paradoxes in stochastic dynamics"
28 September 2009 Robert W. Carpick
University of Pennsylvania
"New insights into dissipative processes: Damping, adhesion, friction,
and wear at the nanometer and atomic scale"
05 October 2009 Bernd Krauskopf
University of Bristol
"Numerical bifurcation analysis applied to systems with delay"
12 October 2009 Hans-Otto Walther
Universität Gießen
"State-dependent delays: Framework, results, open problems"
19 October 2009 Florian Marquardt
Ludwig-Maximilians-Universität München
"Optomechanics - The interaction between light and mechanical motion"
26 October 2009 Judith Frydman
Stanford University
"Molecular Origami: Protein folding and misfolding in health and disease"
02 November 2009 Rob Phillips
California Institute of Technology
"Bacteria Are Stressed Out Too: The Physical Basis of Mechanosensation"
03 November 2009 Wolf Singer
MPI für Hirnforschung
"Distributed processing and temporal codes in cortical networks"
09 November 2009 Eshel Ben-Jacob
Tel Aviv University
"Chips of Hope: NeuroElectronic Hybrids for Brain Repair and Cognitive Machines"
16 November 2009 Dean Astumian
University of Maine
"Thermodynamics and kinetics of molecular motors"
23 November 2009 Peter Abbamonte
University of Illinois
"Why isn't graphene a strongly correlated electron system? - Insights from x-ray attosecond imaging"
30 November 2009 Vladimir Tikhonchuk
Université Bordeaux
"Physics of laser-assisted ion acceleration"
07 December 2009 Andreas Engel
Universität Oldenburg
"Non-equilibrium work and fluctuation theorems"
14 December 2009 Pierre Sens
Laboratoire de Physico-Chimie Théorique, CNRS-ESPCI, Paris
"Membrane-cytoskeleton interactions and mechanical regulation at the cell interface"
07 January 2008Hiroki Sayama
Binghamton University, SUNY, USA
"Self-organizing structures and behaviors of heterogeneous self-propelled particle swarm models"
21 January 2008Jascha Repp
Universität Regensburg
"Current-induced conductance switching of individual molecules"
28 January 2008Achim Richter
TU Darmstadt
"Playing billiards with microwaves - Quantum manifestations of classical chaos"
18 February 2008 Charles Marcus
Harvard University
"Schrödinger's Chip: Semiconductor approaches to quantum information"
31 March 2008Mahir S. HusseinMartin Gutzwiller Fellowship, Award Ceremony
"Role of chaos in the collective response of atom clusters and nuclei"
07 April 2008 Albrecht Ott"Criticality and spontaneous symmetry breaking are part of Hydra's developmental program for axis definition"
14 April 2008 Michael Berry
University of Bristol
"Tsunami asymptotics"
21 April 2008 Roland Netz
Technische Universität München
"Protein adhesion, friction and unfolding: Theoretical approaches"
28 April 2008 Jeroen van den Brink
Universiteit Leiden
"Novel routes to Multiferroics"
05 May 2008 Guido Caldarelli
University of Rome
"Self-organized network evolution coupled to extremal dynamics"
19 May 2008 Marileen Dogterom
AMOLF Amsterdam
"Interaction of dynamic microtubule ends with 'cortical' dynein in vitro"
26 May 2008 Udo Seifert
Universität Stuttgart
"Stochastic thermodynamics"
02 June 2008 Carsten Honerkamp
Universität Würzburg
"Lifestyles of the small and simple - exploring the world of interacting lattice fermions"
09 June 2008 Raymond Shaw
Pennsylvania State University
"Several unsolved problems in the physics of atmospheric clouds"
17 June 2008 Laurens Molenkamp
Universität Würzburg
"Quantum spin Hall effect"
23 June 2008 Alan Tennant
Hahn-Meitner-Institut Berlin
"Magnets as model systems - why simpler is better"
30 June 2008 Piers Coleman
Rutgers University
"Qu-transitions. Phase transitions in the quantum era"
07 July 2008 Manfred Sigrist
ETH Zürich
"How to form Cooper pairs without inversion symmetry?"
14 July 2008 Falk Lederer
Universität Jena
"Shaping light in structured materials"
21 July 2008 Uri Banin
Hebrew University of Jerusalem
"Hybrid metal-semiconductor and semiconductor-semiconductor nanoparticles: From architecture to function"
28 July 2008 Kevin Bassler
University of Houston
"The evolution of networks of competing Boolean nodes"
04 August 2008

Andrea Cavalleri
University of Hamburg

"Stimulated cooperative dynamics in complex solids"
18 August 2008 Ulrich Weiss
University of Stuttgart
"Decoherence and relaxation of coupled qubits"
01 September 2008 Paul Chaikin
New York University
"Toward self-replication with colloids"
22 September 2008 Eberhard Bodenschatz
MPI für Dynamik und Selbstorganisation
"Taming electrophysiological turbulence of the heart"
15 September 2008 Martin Maxey
Brown University, Providence (USA)
"Active particle suspensions: Inertial particles in turbulence to micro-swimmers"
06 October 2008 Fred MacKintosh
Vrije Universiteit Amsterdam
"Non-equilibrium mechanics and fluctuations in the cytoskeleton"
13 October 2008 Nigel E. Hussey
University of Bristol
"Anisotropic scattering and anomalous criticality in high temperature superconductors"
20 October 2008 Peter Wölfle
Universität Karlsruhe
"The Kondo effect: From magnetic alloys to nanoelectronics"
27 October 2008 Andreas Bausch
Technische Universität München
"Cytoskeletal mechanics: Structure and dynamics"
03 November 2008 Qian Niu
University of Texas
"Berry phase effects on spin and charge transport"
10 November 2008 Frédéric Mila
Ecole Polytechnique Fédérale de Lausanne
"Exploring the physics of lattice bosons with quantum magnets"
24 November 2008 John S Briggs
Universität Freiburg
"Max Born's legacy to quantum mechanics:
From entanglement to quantum gravity"
17 November 2008 Alois Loidl
Universität Augsburg
"Frustrated lattices in spinel compounds"
01 Dezember 2008Martin Wolf
Freie Universität Berlin
"Ultrafast dynamics of correlated electron systems"
08 December 2008 Martin Holthaus
Universität Oldenburg
"Near-field scanning thermal microscopy"
15 December 2008Nicolas Brunel
CNRS, Université Paris
"Optimizing information storage in neural circuits:
Consequences on the statistics of synaptic connectivity"
15 January 2007Manolis Antonoyiannakis
American Physical Society
"Peer Review at the journals of Physical Review & Letters"
12 February 2007Stefan Blawid
Qimonda Dresden GmbH & Co.
"Lithography simulations: Enabling leading-edge manufacturing of integrated semiconductor circuits"
19 February 2007Gregor Tanner
The University of Nottingham
"The three-body Coulomb problem: Two electron atoms and the quantum mechanics of three-body collisions and chaos"
26 February 2007Wolfgang Belzig
Universität Konstanz
12 March 2007Hans Kroha
Universität Bonn
"Transport theory of random laser"
26 March 2007Mordechai Segev
Technion Haifa
"Linear and nonlinear waves in photonic lattices: From lattice solitons to photonic quasecrystals, conical diffraction, and Anderson localization"
02 April 2007Miron Amusia
The Hebrew University Jerusalem
"Many-electron atoms as complex systems"
23 April 2007Alexander Lichtenstein
Universität Hamburg
"Prospects of realistic ARPES theory for correlated systems"
14 May 2007Steven L. TomsovicMartin Gutzwiller Fellowship, Award Ceremony
"An irreversibility paradox in simple chaotic systems"
21 May 2007Hiroshi Katayama-Yoshida
Osaka University
"Computational nano-materials design for semiconductor spintronics"
18 June 2007 Eytan Domany
Weizman Institute of Science, Rehovot
"Predicting outcome in cancer: Hope, hype, physics and ... biology"
25 June 2007 Patricio Leboeuf
Université Paris-Sud
"Interacting bosons in random media: Superfluidity versus Anderson localization"
02 July 2007 Lutz Schimanskyl-Geier
Humboldt Universität zu Berlin
"Coupled noisy oscillators" "Coupled noisy oscillators"
23 July 2007 Nilanjana Datta
University of Cambridge
"Perfect transfer of quantum information"
30 July 2007 Andrey V Chubukov
The University of Wisconsin
"Non-analyticities in the thermodynamics of Fermi liquids"
20 August 2007 David Goldhaber-Gordon
Stanford University
"Designer Hamiltonians in the laboratory: Observation of many-body physics in a semiconductor nanostructure"
01 October 2007Martin Heisenberg
Universität Würzburg
"Localized engrams and models of memories in flies"
29 October 2007Andreas Buchleitner
"Open Systems (Dis-)Entanglement: What we know, and what we would like to know"
05 November 2007Ken Ledingham
University of Strathclyde, Glasgow
"A vision for laser induced particle acceleration and applications"
12 November 2007Kazimierz Rzazewski
Polish Academy of Sciences and University Warsaw
"Bose statistics revisited"
19 November 2007André D. Bandrauk
Université de Sherbrooke, Quebec, Canada
"Attosecond molecular physics. The next frontier"
26 November 2007 Hanspeter Helm
Universität Freiburg
"Electric field effects in Rydberg states of triatomic hydrogen"
10 December 2007

Ray Goldstein
University of Cambridge

"Fluid dynamics and the evolution of biological complexity"
17 December 2007 Dirk Brockmann
MPI für Dynamik und Selbstorganisation, Göttingen
"New perspectives on global human traffic, scaling laws and emergent geographic communities"
23 January 2006William J. Firth
University of Strathclyde, Glasgow
"Cavity Solitons: Creation, Control, Complexes"
13 February 2006 Zoltan Toroczkai
Los Alamos National Laboratory
"Conformation networks: An application to protein folding"
27 February 2006Michael Ghil
ENS Paris and University of California, Los Angeles
"The Earth as a Complex System, and a Simple Way of looking at it"
20 March 2006

Alois Würger
CNRS - Université Bourdeaux

"Magnetic field dependence of ht dielectric function of glasses"
24 April 2006Georgy Shlyapnikov
Université Paris-Sud
"Strongly interacting ultracold Fermi gases"
02 May 2006Warren Pickett
University of California, Davis
"Strong coupling superconductivity: Paradigm shifts, alternative universes
22 May 2006Richard Webb
University of South Carolina, USA
"Shot noise and decoherence in nanostructures"
29 May 2006 Pierre Meystre
University of Arizona, Tuscon
"Nonlinear optics of atoms and molecules"
12 June 2006Lawrence S. SchulmanMartin-Gutzwiller-Fellowship, Award Ceremony
"Imaging dynamics: Phase transition, clusters, and geometry from spectral analysis"
13 June 2006Walter Hofstetter
Universität Frankfurt
"Strong correlations in ultracold atoms"
19 June 2006Lakshminarayanan Mahadevan
Harvard University
"Mechanics and mobility"
26 June 2006 Roderich Moessner
CNRS and ENS Paris
"Frustration, liquidity and exotic order"
11 July 2006Felix von Oppen
FU Berlin
"Molecular electronics - Technology or physics?"
17 July 2006Peter Hänggi
Universität Augsburg
"The ring of Brownian motion for complexity: Past, presence and future"
24 July 2006Luiz Davidovich
Rio de Janeiro
"Entanglement and decoherence"
31 July 2006Joerg Schmiedmayer
Universität Heidelberg
"Interference and coherence in 1-d Bose-Einstein-Condensates"
14 August 2006Leonid Glazman
University of Minnesota
"Inelastic electron scattering off magnetic impurities"
18 September 2006Vladimir Falko
Lancaster University
"Introduction to the two dimensional electron physics of graphene (monolayers and bilayers of graphite)"
25 September 2006Helmut Rauch
Atominstitut der Österreichischen Universitäten, Vienna
"Quantum phenomena observed by neutron interferometry"
02 October 2006Klaus von Klitzing
MPI Stuttgart
"Quantum-Hall-Effect and Metrology"
09 October 2006Guillaume Labeyrie
Institut Non Linéaire de Nice
Multiple scattering of light in cold atoms
23 October 2006Pawel Horodecki
Gdansk University of Technology
"Quantum entanglement phenomenon and quantum communication"
06 November 2006Jaroslav Fabian
Universität Regensburg
"Perspectives in spintronics"
13 November 2006Frans A. Spaepen
Harvard University
"Colloidal Systems: 'Analog computers' for simulating the dynamics of crystals and glasses"
27 November 2006Alexander Pukhov
Universität Düsseldorf
"Electron acceleration in the bubble regime"
04 December 2006David M. Leitner
The University of Nevada
"Molecules through the mesoscope"
11 December 2006Georg Maret
Universität Konstanz
"Anderson-localization of light"
18 December 2006Han Woerdman
Leiden University
"Entangled photons"
12 January 2004Jörg P. Kotthaus
LMU Müchen
"Juggling electrons in artificial potentials"
26 January 2004Edouard Brézin
E.N.S. Paris
"Various uses of random matrices"
09 February 2004H. G. Schuster
Universität Kiel
"Adaptation and control in competitive games"
23 February 2004Mark Reed
Yale University
"A decade of molecular electron transport"
02 March 2004Uzy Smilansky
Weizmann Institute Rehovot
"Computational Archeology"
05 April 2004Christian Beck
University of London
"Superstatistics: Theory and Applications"
19 April 2004Friedrich Wagner
MPI für Plasmaphysik Garching, Greifswald
"Progress in Fusion Research"
03 May 2004Dan Kleppner
Massachusetts Institute of Technology, Cambridge
"Rydberg atom physics: The history of a subfield"
10 May 2004Michel Brune
E.N.S. Paris
"Entanglement, quantum measurement and quantum information
with Rydberg atoms and cavities"
17 May 2004Kurt Wiesenfeld
Georgia Institute of Technology, Atlanta
"Stochastic Resonance: Past progress and open questions"
24 May 2004Roman Schnabel
Univ. Hannover, MPI für Gravitationsphysik Hannover
"Gravitational wave detectors: Today and in future"
01 June 2004Jürgen Kurths
Universität Potsdam
"Synchronization phenomena in systems with complicated topology"
07 June 2004Wolfgang Nolting
Humoldt-Universität zu Berlin
"Ferromagnetism: An indestructible hot topic"
08 June 2004Ulrich Schollwoeck
RWTH Aachen
"Simulating the time-evolution of strongly correlated quantum systems"
14 June 2004Boris Shklovskii
University of Minnesota
"Fractionalization induced charge inversion of DNA and gene therapy"
21 June 2004Maya Paczuski
Imperial College London
"Scale-free magnetic networks: Empirical results and a self-organizing model of the coronal field"
05 July 2004Peter Schuster
Universität Wien
"The indispensibility of neutrality in molecular evolution"
12 July 2004Celso Grebogi
Universidade de Sao Paulo
"Fractal skeletons and the plankton paradox"
19 July 2004Italo Guarneri
University Como, Italy
"New and old aspects of nonlinear dynamics unveiled by experiments of cold-atoms optics"
26 July 2004Stefan Luding
TU Delft
"Statistical physics meets mechanics: Structures and pattern formation in granular systems"
02 August 2004Wolfgang Lange
MPQ Garching
"Deterministically engineered single photons from a single ion"
23 August 2004Eshel Ben-Jacob
Tel Aviv University
"Why bacteria go complex - Higher flexibility for better adaptability"
30 August 2004 Henning Samtleben
Universität Hamburg
"Masses and symmetries from extra dimensions"
27 September 2004David Quéré
College de France, Paris
"Slippery textured surfaces"
04 October 2004Fabio Marchesoni
University of Camerino, Italy
"Stochastic Resonance"
11 October 2004G. V. Shlyapnikov
Université de Paris-Sud
"Dynamics of solitons in Bose-condensed gases"
18 October 2004Immanuel Bloch
Universität Mainz
"Seeing the particles beneath the waves -
Beyond mean field physics with Bose-Einstein condensates in optical lattices"
25 October 2004Daniel Esteve
SPEC CEA-Saclay, France
"Control and decoherence of a quantum bit circuit"
08 November 2004Siegfried Grossmann
Universität Marburg
"Boundary layer physics"
15 November 2004Alexander Holevo
Moscow University
"Classical and quantum information: Randomization and entanglement"
22 November 2004Jochen Gemmer
Universität Osnabrück
"From quantum mechanics to thermodynamics?"
29 November 2004Gerard Meijer
Fritz-Haber-Institut der MPG, Berlin
"Manipulation of molecules with electric fields"
13 December 2004 Rüdiger Wehner
University Zürich
"Desert ant navigation: mini-brains - mega tasks - smart solution"


17 January 2005Massimo Inguscio
University of Florence, Italy
"Quantum degenerate atomic gases in ordered and disordered potentials"
07 February 2005Karl Leo
TU Dresden
"Organic semiconductors: Physics and device applications"
14 February 2005Diederik S. Wiersma
LENS Florence, Italy
"Light in and from complex photonic materials"
21 February 2005Hans J. Herrmann
Universität Stuttgart
28 February 2005Volker Meden
Universität Göttingen
"Transport in quantum wires: Inhomogeneities, correlations, and future nano-electronics"
04 April 2005Michael Norman
Argonne National Laboratory
"Pseudogaps, strange metals, and coherent superconductors: The view from ARPES"
11 April 2005David Nelson
Harvard University
"DNA unzipping and motor proteins: Effect of the genetic code"
18 April 2005

Antonio Politi

Martin-Gutzwiller-Fellowship, Award Ceremony
"Dynamics of high-dimensional systems: from a microscopic to a macroscopic description"
25 April 2005Ignacio Cirac
MPQ Garching
"Simulation of quantum many-body systems"
02 May 2005Ennio Arimondo
Universitá di Pisa
"Experiments with Bose-Einstein condensates within optical lattices"
30 May 2005Hans-Peter Herzel
HU Berlin
"Feedbacks, oscillations and synchronization in mammalian cells"
06 June 2005Abraham Nitzan
Tel Aviv University
"Inelastic effects in electron tunneling"
13 June 2005Eberhard Gross
FU Berlin
"Time-dependent density functional theory: Basic concepts and new developments"
20 June 2005Alexander Borst
MPI of Neurobiology, Martinsried
"Adaptation without parameter change: Automatic gain control in Reichardt-type motion detectors"
27 June 2005Alain Arneodo
ENS Lyon
"DNA in chromatin: What can we learn from a multi-scale wavelet analysis of DNA sequences"
04 July 2005Alessandro de Moura
Universidade de Sao Paulo
"Tunneling and non-hyperbolicity in quantum dots"
11 July 2005Leo van Hemmen
TU München
"Mechanosensory localization: What owls, frogs, and scorpions have in common"
25 July 2005William G. Unruh
University of British Columbia, Vancouver
" Dumb Holes "
15 August 2005Pierre Agostini
CEA Saclay, France
"High harmonics attosecond chirp"
05 September 2005 Robin Hudson
"Einstein's quantum, relativity and randomness: A centennial triple fugue"
19 September

Reinhard Werner
TU Braunschweig

"Einstein and quantum mechanics: Are wave functions of individual particles for real?"
26 September 2005Maciej Lewenstein
"Quo vadis optica quantorum?"
17 October 2005Dario Bressanini
Universitá dell'Insubria, Como
"The fascinating Helium Atom"
07 November 2005Hendrik J. Monkhorst
University of Florida
"Chemistry, Physics and the Born-Oppenheimer Approximation"
28 November 2005Angel Rubio
Universidad del Pais Vasco, San Sebastian/Donostia
"Response functions from a TDDFT-based formalism:
Applications to low dimensional structures"
19 Dezember 2005William Bialek
Princeton University
"Maximum entropy models for biological networks"
07 January 2002Shmuel Fishman
Israel Institute of Technology
"Relaxation and diffusion in chaotic systems"
14 January 2002Lorenz S. Cederbaum
Universität Heidelberg
"Intermolecular Coulombic decay in clusters and weakly bound systems"
21 January 2002Jürgen Kuebler
TU Darmstadt
"Magnetism of metals: a density functional view"
28 January 2002Christof Wunderlich
Universität, Hamburg
"Thermally activated escape and stochastic resonance with individual atoms"
04 February 2002Rüdiger Kniep
"Complexity in Chemistry: A + B = AB"
18 February 2002Kai Nagel
ETH Zürich
"Breakdown and recovery in traffic flow models"
25 February 2002Andreas Schadschneider
Universität zu Köln
"Cellular automaton approach to pedestrian dynamics"
04 March 2002James A. Warren
NIST, Gaithers Burg, MD
"Phase field modeling of crystal growth, grain boundaries and electrodeposition: A unified approach"
08 April 2002Jonathon Howard
MPI CBG Dresden
"Microtubules, Motors and Mechanoreceptors"
15 April 2002Alfredo Ozorio d' Almeida
Martin-Gutzwiller-Fellowship, Award Ceremony
"The birth of 'Semiclassics': A personal view of the Gutzwiller Trace Formula"
22 April 2002Arkady Pikovsky
Universität Potsdam
29 April 2002Johannes Voit
Dt. Sparkassen- und Giroverband
"From Brownian motion to operational risk: Physics and financial markets"
13 May 2002Giulio Casati
Univ. Como
"Efficient quantum computing of complex dynamcis"
27 May 2002R. Luest
Dt. Klimarechenzentrum Hamburg
"From the bottom of the sea, down to earth into space"
03 June 2002Antti-Pekka Jauho
Micro- and Nanotechnology Research Center, Lyngby, Denmark
"Mesoscopic Coulomb drag"
10 June 2002Robert Brooks
Technion Haifa
"Spectral properties of Riemann surfaces"
17 June 2002Louis Kauffman
University of Illinois, Chicago
"Knots and Physics"
24 June 2002Isabel Darcy
University of Texas
"Tied in Knots: Applications of knot theory to the study of protein mechanism"
01 July 2002 Sergey Novikov
Landau Institute Moscow and University of Maryland
"Topological phenomena in normal metals"
15 July 2002Jörg Bilgram
ETH Zürich
"Solidification far from equilibrium - Morphologies of xenon crystals
22 July 2002Alexander Grosberg
University of Minnesota
"Physics of charge inversion in chemical and biological systems"
05 August 2002Pierre Gaspard
Universite Libre de Bruxelles
"Microscopic chaos and transport phenomena"
12 August 2002Nicolai Chernov
University of Alabama
"Dynamics of a massive piston in an ideal gas"
19 August 2002Denis J. Evans
Australian National University
"The fluctuation theorem"
26 August 2002Michael Menzinger
University of Toronto
"Reactive Flows in Toronto"
23 September 2002Patrick Tabling
ENS Paris
"Some physical and dynamical aspects in microfluid systems"
30 September 2002Manuel A. Fortes
Universidade Tecnica de Lisboa
"Solid and liquid foams: Concepts and rheological properties"
07 October 2002Richard Gill
University Utrecht
"Passion at a distance of 30 sigma?"
14 October 2002Bernhard Kramer
University Hamburg
"Scaling at the Anderson transition"
21 October 20002Eric Clément
Université Paris IV
"Fragility of granular matter: An experimentalist's point of view"
28 October 2002Michael E. Fisher
University of Maryland
"The SAGA of COULOMBIC CRITICALITY: From Debye and Hückel to Ginzburg and beyond"
04 November 2002Hermann Grabert
Universität Freiburg
"Electron-electron interactions in mesoscopic wires"
11 November 2002Eric J. Heller
"From quantum corrals to concert halls: Waves in confined spaces"
18 November 2002Ramamurti Shankar
Yale University
"Renormalization group for interacting fermions - a pedagogical introduction"
25 November 2002Beate Schmittmann
Virginia Tech
"Driven diffusive systems: Surprises far from thermal equilibrium"
02 December 2002Clemens Bechinger
Universität Konstanz
Colloidal suspensions as analog computers for complex tasks"
09 December 2002T.W. Haensch
MPQ Garching
"Precision spectroscopy with ultra-short pulses"


13 January 2003Philippe Blanchard
Universität Bielefeld
"Complex random network: The origin of scale-free graphs, percolation, epidemic thresholds and all that"
20 January 2003Oriol Bohigas
LPTMS, Orsay
"Quantum chaos: From the atomic nucleus to the Riemann zeta function"
27 January 2003Nimrod Moiseyev
Technion Haifa
"NON HERMITIAN QUANTUM MECHANICS: Theory and applications to problems that hard/impossible to solve by the conventional QM"
03 February 2003Ingolf Volker Hertel
Max-Born-Institut Berlin
"Ultrafast dynamics and H-transfer in clusters and biologically relevant molecules"
10 February 2003Bruno Eckhardt
University Marburg
"Chaotic mixing"
17 February 2003Ernst H. Brandt
MPI for Metals Research Stuttgart
"Statics and dynamics of the vortex lattice in high-Tc superconductors"
24 February 2003 Philipp Gegenwart
CPfS Dresden
"Quantum criticality in heavy Fermon systems"
17 March 2003T. Maurice Rice
ETH Zürich
"The diversity of electronic states in solids - A challenge for renormalization group methods"
07 April 2003Michael F. Crommie
University of California at Berkeley
"STM studies of surface Kondo impurities and clusters"
14 April 2003Matthias Steinmetz
Astrophysikalisches Institut Potsdam (AIP)
"Structure formation in a preposterous universe"
28 April 2003Hans Briegel
LMU München
"Multi-particle entanglement: Concepts and applications"
12 May 2003Marek Ploscajczek
"Description of the structure of weakly bound/unbound correlated quantum systems"
19 May 2003Werner Hanke
Universität Würzburg
"Where are we at in the microscopic theory of high-Tc superconductivity?"
26 May 2003Raymond Kapral
University Toronto
Martin-Gutzwiller-Fellowship, Award Ceremony
"Knotty problems in nonlinear dynamics"
02 June 2003Julius Wess
LMU Müchen
"Field theory and quantum mechanics on deformed spaces"
10 June 2003A. K. Wroblewski
Warsaw University
"Sense and nonsense in bibliometrics"
16 June 2003D. D. Osheroff
Stanford University
"The importance of interactions between TS in glassy materials at low temperatures:
A historical perspective"
23 June 2003Daniel Robert
University of Bristol
"The ears of insects: Microscale sensors and auditory nanomechanics"
30 June 2003Andreas Schäfer
Universität Regensburg
"Quantum chromodynamics and random matrix theory"
07 July 2003Frank Cichos
TU Chemnitz
"Diffusion in nanostructures"
17 July 2003Ian Affleck
Boston University
"Conductance of Luttinger liquid y-junctions"
21 July 2003Ralf Metzler
NORDITA Copenhagen
"Topology matters: Some aspects of DNA physics"
04 August 2003Piet Brouwer
Cornell University Ithaka, USA
"Quantum pumps for charge and spin"
18 August 2003Klaus Dietz
"Quantum dynamics in open systems"
25 August 2003

Yannis Kevrekidis
Princeton University

"Initializing at will: Equation-free modeling and experimentation"
06 October 2003Claude Godreche
CEA Saclay
"Nonequilibrium dynamics of ferromagnetic spin systems"
20 October 2003 A. J. Hudspeth
The Rockefeller University, New York
"Making an effort to listen: Mechanical amplification by novel molecular motors in the ear"
27 October 2003Rainer Blatt
Universität Innsbruck
"Quantum computer - dream and realization"
03 November 2003Gerard t'Hooft
Utrecht University
"Quantum Mechanics at the Black Hole Horizon"
10 November 2003Hans-Jürgen Stöckmann
Universität Marburg
"Transmission studies in open microwave billiards"
17 November 2003Gerhard Birkl
Universität Hannover
"Atomic quantum systems in optical mircro-structures"
24 November 2003Heiner Igel
LMU München
"Computational wave propagation in seismology"
01 December 2003Gerd Leuchs
Universität Erlangen-Nürnberg
"Quantum properties of optical fiber solitons"
08 December 2003Wolfgang Zinth
LMU München
"Photosynthesis - ultrafast reactions for highly efficient energy conversion"
15 December 2003Michael Hortmann
Universität Bremen
"Cryptography and quantum mechanics"
23  March 2000Todd Ditmire
"Studies of intense laser driven Coulomb explosions in large clusters and applications to deuterium nuclear fusion"
17 April 2000Berthold-Georg Englert
Universitaet Ulm und MPQ Garching:
"Quantitative Wave-Particle-Dualism"
08 May 2000I. Mertig
"Tunneling magneto-resistance: a new phenomenon?"
15 May 2000P. Grassberger
"Why it helps to be biased and opportunistic when doing simulations"
22 May 2000Eric Heller
Harvard University
"Putting Quantum Phase Space to Work: From Chaos to Chemistry"
29 May 2000Celada
"Modelling the immune system and why"
05 June 2000Wilhelm Zwerger
LMU München
"Topological effects and universal force oscillations in nanocohesion"
19 June 2000M. Wilkens
University Potsdam
"Quantum Games"
03 July 2000R. N. Mantegna
"Physics of Stock Markets"
10 July 2000Achim Wixforth
Center for NanoScience, LMU Muenchen
"Nano-Quakes on a Chip: Surface acoustic waves in semiconductor physics"
17 July 2000Ken Taylor
"Laser-driven 3-body Coulomb dynamics in atoms and molecules''
24 July 2000H. Weidenmüller ''Recent Developments in Random Matrix Theory''
31 July 2000Detlef Duerr
Universitaet Muenchen
''Bohmian Mechanics-Foundation of Quantum Mechanics''
11 September 2000Dominique Delande
"Beyond Periodic Orbit Theory and Random Matrix Theory in Atomic Physics''
18 September 2000Guenter Radons
TU Chemnitz
''Theoretical Physics meets Engineering: Nonlinear Dynamics of Waterjet Cutting''
25 September 2000Gerd Schoen
Universitaet Karlsruhe
''Josephson Qubits und der Quantenmessprozess''
30 October 2000

Herbert Levine
University San Diego

''The Dictostelium Amoeba: A motion-dominated lifecycle''
06 November 2000Michael Schreiber
TU Chemmitz
''Correlated Electrons in the Quantum Coulomb Glass and in Parabolic Quantum Dots''
13 November 2000D. Vollhardt
Univ. Augsburg
''Strongly Correlated Electron Systems: Problems, Progress and Perspectives''
20 November 2000Peter Lambropoulos
University of Crete
''Two- and Three-Electron Atoms Driven by Laser Fields''
27 November 2000Hans Herrmann
Univ. Stuttgart
''The form of dunes''
05 December 2000Seth Putterman
University of California
11 December 2000Joachim Hilgert
TU Clausthal
''Introduction to the Mathematical Problems of Quantum Chaos''
18 December 2000Werner Ebeling
Humboldt-Universität Berlin
''Complex Dynamics of Active Brownian Particles''


08 January 2001Werner Pesch
Universität Bayreuth
''Spirals and Spiral Defect Chaos in Rayleigh-Benard Convection''
15 January 2001Nicolas Agrait
Universidad Autonoma de Madrid
"Atomic Contacts and Atomic Chains"

22 January 2001

Michael Thoss
TU München
"Semiclassical Description of Molecular Dynamics"
29 January 2001 Dirk Helbing
TU Dresden/Traffic Sciences
"Traffic and Other Self-Driven Many-Particle Systems"
05 February 2001Mathias Bode
University  Münster and Cortologic AG Berlin
"Binocular Rivalry: On the Modelling of Decision Processes in the Visual Cortex"
12 February 2001Herbert Wagner
LMU München
"Morphology of Large-Scale Structures in the Universe"
19 February 2001Oliver Benson
Universität Konstanz
"Novel Light Sources from Nanoparticles coupled to Microcavities: Quantum Optics on a Nanometer Scale"
26 February 2001Stephan Diekmann
Universität Jena
"Electrons in Biology - Structure and Function of Oxydoreductases"
12 March 2001David Sherrington
University Oxford
"Magnets, microchips, memories and markets: statistical physics of complex systems"
19 March 2001Martin Riedmiller
Universität Karlsruhe
"Reinforcement Learning in Cooperative Multi Agent Systems"
02 April 2001Richard Prange
Martin-Gutzwiller-Fellowship, Award Ceremony
"Special Eigenstates in Quantum Chaos"
09 April 2001Gert-Ludwig Ingold
Universität Augsburg
"Josephson Effect and Phase Fluctuations"
23 April 2001L. Schimansky-Geier
Humboldt-Universität Berlin
"Noise in excitable systems"
30 April 2001Hans De Raedt
Universität Groningen
"If we would have a quantum computer what can we do with it?"
07 May 2001Konstantin Efetov
Ruhr-Universität Bochum
"Quantum Interference and Coulomb Interaction in Arrays of Tunnel Junctions"
14 May 2001Kurt Binder
Universität Mainz
"Monte Carlo Simulations of Surface - Induced Order and Disorder"
21 May 2001Gustav Gerber
Universität Würzburg
"Optimal Control of Quantum Dynamics by Adaptive Femtosecond Pulse Shaping"
28 May 2001A. J. Leggett
University of Illinois
"Superfluidity, phase coherence and the new Bose-condensed alkali gases"
11 June 2001Carl Dettmann
University of Bristol
"Perturbation theories of stochastic chaos"
18 June 2001Gero Vogl
Hahn-Meitner-Institut Berlin
"Quantum interferences and atomic jumps in solids"
25 June 2001Peter Hänggi
Universität Augsburg
"Brownian Motors"
02 July 2001Peter M. Koch
State University of New York
"Phase Control of Atomic Dynamics in Strong, Bichromatic Fields"
09 July 2001Rudolf Friedrich
Universität Stuttgart
"Analysis of Stochastic Systems with Applications in Turbulence, Traffic and Medicine"
16 July 2001Herbert Walther
MPQ Garching
"Quantum Phenomena of Single Atoms"
30 July 2001Roman Kotecky
Universität Prag
"Mathematics of phase transitions: from finite size effects to zeros of partition function"
31 July 2001Sergey Ganichev
Universität Regensburg
"Conversion of spin into directed electric current in quantum wells"
17 September 2001Annette Zippelius
Universität Göttingen
"Critical Dynamics of Gelation"
08 October 2001Turgay Uzer
"Rydberg Electron Dynamics in Many (>2) Degrees-of-Freedom"
15 October 2001Kestutis Pyragas
Semiconductor Physics Institute Vilnius, Lithuania
"Control of chaos via an unstable delayed feedback controller"
22 October 2001Jean Dalibard
Laboratoire Kastler Brossel Paris
"Bose-Einstein Condensates: Quantum Coherence and Superfluidity"
29 October 2001

Gregor Hackenbroich
Universität Essen

"Random light: From localization to random lasers"
05 November 2001Leonid P. Shilnikov
Novgorod University
"Basic bifurcations of dynamical systems"
12 November 2001Siegfried Hess
TU Berlin
"Flow properties of complex fluids"
19 November 2001R. Sauerbrey
Universität Jena
"Interaction of intense laser radiation with matter"
26 November 2001Uzy Smilansky
Weizmann Institut
"Counting Nodal Domains - from Chladni to Quantum Chaos"
03 December 2001Eckehard Schöll
TU Berlin
"Transport in nanostructures - a paradigm for complex nonlinear dynamics and pattern formation"