Talks

Perfect Adaptation in Biological Networks

A distinctive feature of many biological systems is their ability to adapt to persistent stimuli or disturbances that would otherwise drive them away from a desirable steady state. This resulting stasis enables reliable function across a wide range of external environments. We focus on a stringent form of this behavior—robust perfect adaptation (RPA)—which remains resilient to certain network and parameter perturbations. As in engineered control systems, RPA is not incidental: it requires the regulating network to satisfy specific, unavoidable structural constraints. Using examples from systems biology and synthetic biology, we show how these constraints arise in natural and engineered circuits. We argue that identifying the structural basis of RPA allows us to move beyond implementation details and provides a principled lens for understanding regulatory complexity and information processing in biological systems

Probing unconventional magnetism in modern quantum simulators: from tweezer arrays to Wigner molecular crystals

The ability to engineer quantum matter offers new opportunities for studying correlated magnetism and emergent many-body phenomena. In this talk, I will explore this perspective across two distinct settings: dipolar tweezer arrays and twisted moiré materials. In the former, I will show how the continuous tunability of the lattice, in conjunction with long-range interactions, offers a simple route to stabilizing a chiral spin liquid state. I will then argue that the other tools available on this platform — such as local addressing and readout — offer a path to preparing and studying this topological state. In the latter, I will introduce Wigner molecular crystals as a novel platform for studying correlated magnetism, enabling the observation of helical spin liquid states and fluctuation-driven orbital ferromagnetism. While disparate, these two platforms are connected by an equivalent description of their low-energy physics; making this connection, I will demonstrate how the two platforms enable complementary perspectives and tools for exploring correlated phenomena.

Extreme vulnerability to intruder attacks destabilizes network dynamics

Consensus, synchronization, formation control, and power grid balance are all examples of virtuous dynamical states that may arise in networks. Here we focus on how such states can be destabilized from a fundamental perspective; namely, we address the question of how an intruder agents within an otherwise functioning network may compromise its dynamics. We show that a single adversarial node coupled via adversarial connections to one or more other nodes is sufficient to destabilize the entire network, which we prove to be more efficient than targeting multiple nodes. Then, we show that concentrating the attack on a single low-indegree node induces the greatest instability, challenging the common assumption that hubs are the most critical nodes. This leads to a new characterization of the vulnerability of a node, which contrasts with previous work, and identifies low-indegree nodes (as opposed to the hubs) as the most vulnerable components of a network. Our results are derived for linear systems but hold true for nonlinear networks, including those described by the Kuramoto model. Overall, these findings highlight an intrinsic vulnerability of technological systems, such as autonomous networks, sensor networks, power grids, and the internet of things, with implications that extend also to the realm of complex social and biological networks.

Exploring Valleytronics and Attosecond Physics in quantum materials through Strong-Field Optical Responses

Nonlinear light-matter interaction provides a powerful framework for probing and controlling electronic dynamics beyond the perturbative regime. In recent years, strong-field driven high harmonics generation (HHG) in solids has emerged as a sensitive probe of topology, Berry curvature and valley-selective carrier dynamics, enabling access to ultrafast electronic processes on femtosecond and attosecond timescales. In two-dimensional semiconductors, valley-selective excitation using tailored laser pulses enables optical control of valleys in momentum space. A combination of bichromatic pump and driver fields produces pronounced chiral-sensitive frequency mixing in HHG spectra, where the emitted harmonics encode information about valley polarization, symmetry breaking, and helicity-dependent carrier dynamics. The nonlinear optical response reveals strong sensitivity to the interplay between Berry curvature and ultrafast interband coherence, establishing frequency mixing spectroscopy as a promising route for valley manipulation and detection. Furthermore, the role of structured light fields in controlling valley population dynamics and nonlinear emission highlights new opportunities for ultrafast valleytronic applications. The talk will also address nonlinear strong-field phenomena in Weyl semimetals, where topological band structure and chirality strongly influence the harmonic emission. A tailored laser driving field can generate broadband high harmonics and isolated attosecond pulses from Weyl systems through coupled interband and intraband electronic motion. The generation of attosecond pulses from solids further demonstrates the potential of topological materials as compact ultrafast light sources operating at extreme timescales. In a nutshell, we attempt to establish nonlinear optical response as a versatile platform for exploring valley physics, topological dynamics, and ultrafast quantum phenomena in condensed matter systems.

Quantum Dynamics Seminar: tba

Colloquium: Statistical Physics of Learning in the Age of Attention

Over the past decades, statistical physics has provided a powerful framework for analyzing learning in high-dimensional models, revealing phase transitions, fundamental limits on generalization, and the role of algorithms and architectures. In this talk, I will discuss how these ideas are now being extended beyond classical perceptron-type models to attention-based architectures that process sequences of tokens, opening a path toward a statistical physics theory of transformers.

Emergent Gauge Fields in Quantum Condensed Matter

It has long been understood that the exact (“fundamental”) gauge symmetry of the electromagnetic fields plays an important role in the theory of quantum materials. What has come into focus more recently is that there exist essential properties of quantum phases of matter that are best understood in terms of an effective field theory with emergent gauge fields, rather than (or in addition to) in terms of broken symmetries. Here, gauge invariance is not a symmetry of the microscopic problem but is rather an efficient representation of the low energy physics. As time permits, I will discuss recent theoretical results that suggest that exotic “resonating valence-bond” fluids, describable by emergent gauge theories, might exist in a much broader range of experimentally accessible platforms than has been previously appreciated.

The emergent "graviton" in the fractional quantum Hall effect

In fractional quantum Hall states, electrons self-organize into a strongly interacting fluid with nontrivial emergent properties. It has recently been understood that fractional quantum Hall fluids accommodate one or several spin-2 excitations, which have been argued to be condensed-matter analogues of the graviton. In this talk we will review the origin of the idea of the graviton and the basic physics of the fractional quantum Hall effect. We then discuss a recent experiment claiming observation of a graviton-like mode in fractional quantum Hall effect and its broader implications.

Quantum Dynamics Seminar: tba

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