09:00  09:45

Martin Zwierlein
(Massachusetts Institute of Technology)
Geometric Squeezing and Crystallization of Bosonic Quantum Hall States

09:45  10:15

Eric Bertok
(GeorgAugustUniversität Göttingen)
Splitting of topological charge pumping in an interacting twocomponent fermionic RiceMele Hubbard mode
A Thouless pump transports an integer amount of charge when pumping adiabatically around a singularity.
We study the splitting of such a critical point into two separate critical points by adding a Hubbard interaction. Furthermore, we consider extensions to a spinful RiceMele model, namely a staggered magnetic field or an Isingtype spin coupling, further reducing the spin symmetry.
The resulting models additionally allow for the transport of a single charge in a twocomponent system of spinful fermions, whereas in the absence of interactions, zero or two charges are pumped. In the SU(2)symmetric case, the ionic Hubbard model is visited once along pump cycles that enclose a single singularity. Adding a staggered magnetic field additionally transports an integer amount of spin while the Ising term realizes a pure charge pump.
We employ realtime simulations in finite and infinite systems to calculate the adiabatic charge and spin transport, complemented by the analysis of gaps and the manybody polarization to confirm the adiabatic nature of the pump. The resulting charge pumps are expected to be measurable in finitepumping speed experiments in ultracold atomic gases, for which the SU\((2)\) invariant version is the most promising path. We discuss the implications of our results for a related quantumgas experiment by Walter \textit{et al.} [arXiv:2204.06561].

10:15  10:45

coffee break

10:45  11:30

Oded Zilberberg
(University of Konstanz)
Spinor topology and spatiotemporal engineering of manybody topological states
Topological insulators (TIs) have been successfully demonstrated in photonic, electrical, phononic, acoustic, atomic, and polaritonic systems. The ubiquitousness of topological effects stems from a common origin geometrical frustration of wavefunctions in space and time. In my talk, I will present a unifying semiclassical treatment that extends the modern theory of polarization to any spinor degree of freedom. We dub this approach spinor topology. I will furthermore introduce a corresponding group theoretical approach to obtain highorder topology. If time permits, I will present a dressed Floquet theory that includes AC stark shifts, thus faithfully describing driven interacting systems. Last, I will discuss a classicaltoquantum transition in a drivendissipative system where a nonHermitian exceptional point is erased by manybody interactions.

11:30  12:00

Luca Asteria
(Hamburg University)
Microscopy of ultracold atoms in optical lattice via quantum gas magnification
In this contribution we present results on quantum gas magnification as a microscopy
tool for ultracold atoms in optical lattices.
We developed a matter wave optics protocol which magnifies the atomic density
distribution by almost two orders of magnitude [1], allowing to image the magnified
cloud in a singleshot and with sublattice resolution by using standard optical
imaging techniques. This approach works with 3D systems
with many particles per lattice site, because it does not have the limitations of a small
depth of focus and of light induced collisions.
We demonstrate sublattice
resolution by observing the dynamics within the lattice sites after a
lattice potential quench, and we realize singlesite addressing using magnetic resonance techniques.
We report on a novel phenomenon that occurs in the regime of many particles
per lattice site when introducing a strong force into the system; this makes the correlated tunneling of
pairs of atoms the relevant dynamical process and causes the spontaneous formation of a density wave [2].
Quantum gas magnification opens the path for spatially resolved studies of new
quantum manybody regimes, like e.g. 3D systems, orbital lattices, and lattice
geometries with smaller lattice spacing.
We finally discuss the novel multifrequency scheme for optical lattices with dynamically tunable geometry and present experimental results and possible multifrequency realizations of tunable 3D lattices and quasicrystals [3].
References
[1] L. Asteria et al., Nature 599, 571575 (2021)
[2] H. P. Zahn et al., PRX 12, 021014 (2022)
[3] M. N. Kosch et al., https://arxiv.org/abs/2207.03811

12:00  13:00

Lunch

13:00  14:00

discussion

14:00  14:45

Jacqueline Bloch
(Centre National de la Recherche Scientifique (CNRS))
Nonlinear photonics in topological polariton lattices
I would like to send the abstract of my talk later.
Sorry for the inconvenience

14:45  15:30

Iacopo Carusotto
(NOCNR BEC Center)
Excitations and dynamics of fractional quantum Hall fluids of light and of atoms

15:30  16:00

Lukas Sieberer
(University of Innsbruck)
Relaxation to a paritytime symmetric generalized Gibbs ensemble after a quantum quench in a drivendissipative Kitaev chain
The construction of the generalized Gibbs ensemble, to which isolated integrable quantum manybody systems relax after a quantum quench, is based upon the principle of maximum entropy. In contrast, there are no universal and modelindependent laws that govern the relaxation dynamics and stationary states of open quantum systems, which are subjected to Markovian drive and dissipation. Yet, as we show, relaxation of drivendissipative systems after a quantum quench can, in fact, be determined by a maximum entropy ensemble, if the Liouvillian that generates the dynamics of the system has paritytime symmetry. Focusing on the specific example of a drivendissipative Kitaev chain, we show that, similarly to isolated integrable systems, the approach to a paritytime symmetric generalized Gibbs ensemble becomes manifest in the relaxation of local observables and the dynamics of subsystem entropies. In contrast, the directional pumping of fermion parity, which is induced by nontrivial nonHermitian topology of the Kitaev chain, represents a phenomenon that is unique to relaxation dynamics in drivendissipative systems. Upon increasing the strength of dissipation, paritytime symmetry is broken at a finite critical value, which thus constitutes a sharp dynamical transition that delimits the applicability of the principle of maximum entropy. While we focus here on the specific example of the Kitaev chain, our results generalize readily to all paritytime symmetric and integrable drivendissipative systems that are described by or can be mapped to noninteracting fermions.

16:00  16:45

coffee break

16:45  17:15

Hongzheng Zhao
(Max Planck Institute for the Physics of Complex Systems)
Anomalous random multipolar driven insulators
It is by now well established that periodically driven quantum manybody systems can realize topological nonequilibrium phases without any equilibrium counterpart. Here we show that, even in the absence of time translation symmetry, nonequilibrium topological phases of matter can exist in aperiodically driven systems for tunably parametrically long prethermal lifetimes[1]. As a prerequisite, we first demonstrate the existence of longlived prethermal Anderson localization in two dimensions under random multipolar driving[2]. We then show that the localization may be topologically nontrivial with a quantized bulk orbital magnetization even though there are no welldefined Floquet operators. We further confirm the existence of this anomalous random multipolar driven insulator by detecting quantized charge pumping at the boundaries, which renders it experimentally observable.
[1] Phys. Rev. B 105, 245119 (2022)
[2] Phys. Rev. Lett. 126, 040601 (2021)

17:15  17:45

Youjiang Xu
(Johann Wolfgang GoetheUniversität Frankfurt)
Invisible flat bands on a topological chiral edge
We prove that invisible bands associated with zeros of the singleparticle Green's function exist ubiquitously at topological interfaces of 2D Chern insulators, dual to the chiral edge/domainwall modes. We verify this statement in a repulsive Hubbard model with a topological flat band, using realspace dynamical meanfield theory to study the domain walls of its ferromagnetic ground state. Moreover, our numerical results show that the chiral modes are split into branches due to the
interaction, and that the branches are connected by invisible flat bands. Our work provides deeper insight into interacting topological systems.

18:00  18:30

discussion

18:30  19:30

dinner

19:30

Poster session (main building, 2nd floor)
