Annual FOR 5522 Workshop

18 May 2026, 14:00 → 20 May 2026, 20:00 Europe/Berlin

Convention Centre by the Observatory

Fabian Heidrich-Meisner (Georg-August-Universität Göttingen)

Annual FOR 5522 Workshop

Topics

• Eigenstate Thermalization

• Transport

• Quantum Chaos

• Weak ergodicity breaking

• Many-body localization

Invited Speakers

• André  Eckardt, TU Berlin

• Huanqian Loh, Duke University

• Tomaž Prosen, University of Ljubljana

• Roser Valentí, University of Frankfurt

• Christof Weitenberg, TU Dortmund

Organizer

• Fabian Heidrich-Meisner, Unversity Göttingen

Contact

• Fabian Heidrich-Meisner: fabian.heidrich-meisner@uni-goettingen.de
• Anke Oude-Aost: anke.oude-aost@theorie.physik.uni-goettingen.de

 

This Event is organized by DFG Research Unit FOR 5522.

 

Monday 18 May

Invited Talks

1 Phase microscopes for quantum gases: from weakly to strongly correlated regimes

Quantum gas microscopes probe quantum many-body lattice states via projective measurements in the occupation basis, enabling access to various density and spin correlations. Phase information, however, cannot be directly obtained in these setups. Here we introduce a phase microscope for quantum gases, which measures the local phase profiles with single lattice-site resolution [1], based on Fourier-space manipulation in a matter-wave microscope [2]. We use the phase microscope to study the coherence properties of an ultracold Bose gas in a two-dimensional optical lattice across the thermal phase transition. Furthermore, we discuss protocols for many-body phase microscope, which will give access to various long-range off-diagonal correlators in experimentally realistic settings, which are highly relevant for characterizing many-body phases such as d-wave superconductors or fractional Chern insulators [3].

Speaker: Christof Weitenberg (TU Dortmund)

2 Quantum spin liquids: from first principles to materials

Recent news from QSL in materials!

Speaker: Roser Valenti

15:30 Coffee Break

RDM Session

3 RDM in FOR 5249

How they run RDM in their RU

Speaker: Roser Valenti (U Frankfurt)

4 RDM in FOR 5688

How they do RDM in Berlin

Speaker: André Eckardt (TU Berlin)

5 RDM in FOR 5413

How FOR 5413 does RDM

Speaker: Igor Lesanovsky (GNOI)

6 RDM in FOR 5522

How we do RDM in FOR 5522

Speaker: Markus Heyl (GNOI)

17:00 Break

FOR Talks

7 Dynamical preparation of U(1) quantum spin liquid lakes in an analogue quantum simulator

Locally constrained gauge theories underpin our understanding of fundamental interactions in particle physics and the behaviour of quantum materials. In strongly correlated systems, they can give rise to quantum spin liquids that lack conventional order and are defined by coherent superposition of many-body configurations. Realising and probing such exotic states experimentally remains challenging due to the difficulty of engineering local constraints and detecting coherences between many-body states. In this talk, I will present a large-scale realisation of a two-dimensional U(1) lattice gauge theory with ultracold atoms in an optical superlattice with over 1000 sites. We explore non-equilibrium dynamics and investigate non-adiabatic protocols for the preparation of Rokhsar–Kivelson quantum spin liquid lakes within the constrained Hilbert space. Our results establish non-equilibrium quantum simulation protocols as a powerful route for accessing exotic, highly-entangled states beyond those hosted by the engineered Hamiltonian in thermal equilibrium.

Speaker: Irene Prieto Rodriguez (LMU/MPQ)

8 Probing Strongly Correlated Quantum Systems Out of Equilibrium with Neutral Atoms in Optical Lattices

Project E4

Speaker: Monika Aidelsburger

Tuesday 19 May

Invited Talks

9 Hilbert Space Fragmentation in a Rydberg Quantum Simulator

invited talk

Speaker: Huanqian Loh (Duke University)

FOR Talks

10 Realizing quantum spin liquids using U(1) lattice gauge theories

Recent results!

Speaker: Melissa Will (TUM School of Natural Sciences, Munich Center for Quantum Science and Technology)

10:15 Coffee Break

FOR Talks

11 A Tale of Cages and Bathtubs

This talk starts from Fock-space cages, which are localized many-body eigenstates stabilized through destructive interference in the state space. I then turn to the spectral setting that makes such states possible: constrained spin chains with an exponentially large manifold of exact zero modes, a hard gap around zero energy, and otherwise chaotic bulk dynamics described by chiral random matrix theory. This provides a simple setting in which Fock-space localization and quantum chaos coexist.

Speaker: Cheryne Jonay

12 Quantum many-body cages

We identify the many-body counterpart of flat bands, which we call many-body caging, as a general mechanism for non-equilibrium phenomena such as a novel type of glassy eigenspectrum order and many-body Rabi oscillations in the time domain. We focus on constrained systems of great current interest in the context of Rydberg atoms and synthetic or emergent gauge theories. We find that their state graphs host motifs which produce flat bands in the many-body spectrum at a particular set of energies. Basis states in Fock space exhibit Edwards-Anderson type parameters in the absence of quenched disorder, with an intricate, possibly fractal, distribution over Fock space which is reflected in a distinctive structure of a non-vanishing post-quench long-time Loschmidt echo, an experimentally accessible this http URL general, phenomena familiar from single-particle flat bands manifest themselves in characteristic many-body incarnations, such as a reentrant `Anderson' delocalisation, offering a rich ensemble of experimental signatures in the abovementioned quantum simulators. The variety of single-particle flat band types suggests an analogous typology--and concomitant phenomenological richness to be explored--of their many-body counterparts.

Speaker: Tom Arie Ben Ami (Universitat Augsburg)

13 Erbium-Lithium: A quantum-gas mixture with extreme mass imbalance

Creating quantum mixtures can be a challenging, yet highly awarding goal. While many quantum mixture experiments rely on atoms of different spin states or isotopes, the approach of this experiment relies on two atoms as far apart as currently reachable. While lithium-6 is a fermionic and light atom, erbium-166 is a bosonic and heavy counterpart. This strongly mass imbalanced mixture possesses a low scattering tuneout wavelength, enabling individual control of lithium within erbium.
By that means, we want to study the thermalisation of an impurity within a bosonic background, namely a bose polaron.

Speaker: Jonas Auch (GNOI)

12:15 Lunch Break

Invited Talks

14 Non-standard exchange statistics in one dimension: The anyon Hubbard model and beyond

The anyon Hubbard model has recently been realized experimentally by the Greiner group in Harvard using a driven optical lattice. It can be represented by a bosonic tight-binding chain with number-dependent Peierls phases. I will given an introduction to the model and argue that it describes non-trivial particle exchange in one spatial dimension, associated with non-trivial Berry phases around Fock-space loops. These phases make themselves felt not only in the ground state (e.g. via the build-up of Friedel oscillations), but also in the dynamics. Of particular interest are chiral bound states of two and three particles that exist both inside and outside the continuum. I will, finally, introduce a recently proposed lattice model for so called traid anyons that are defined by non-trivial three-particle braiding in one dimension.

Speaker: André Eckardt (TU Berlin)

FOR Talks

15 Large deviations and conditioned monitored quantum systems: a tensor network approach

Coexistence of different dynamical phases is a hallmark of glassy behavior, widely studied in classical systems via large deviation theory. Similar phase coexistence has been suggested in quantum many-body systems, but a systematic study has been challenging due to the lack of suitable methods. Here, I present a tensor network framework that enables large deviation analysis in large quantum systems. Using this approach, we identify first-order dynamical phase transitions in a monitored discrete-time many-body quantum dynamics. Importantly, this framework also allows us to access conditioned quantum states, providing a microscopic view of the dynamical phases and their coexistence. This talk will discuss both the methodology and the new insights it provides into quantum dynamical phase transitions.

Speaker: María Cea Fernández (Max Planck Institute of Quantum Optics)

15:15 Coffee Break

FOR Talks

16 Quench cooling of interacting quantum many-body systems

Interaction quenches are usually associated with heating of isolated quantum system. However, starting from non-zero temperature interaction quenches can also cool quantum systems. This is shown explicitly for the 1d Hubbard model using numerical methods, perturbative analytical methods and Bethe ansatz results. Depending on the parameter regime cooling can occur on prethermal time scales or even in the long-time limit.

Speaker: Stefan Kehrein (UPTP)

Poster Session

17 Dinner

Wednesday 20 May

Invited Talks

18 Multifractal dynamical response

tba

Speaker: Tomaz Prosen

FOR Talks

19 Linking the relaxation frequencies to off-diagonal eigenstate thermalization in a disordered spin-1/2 XX ladder

The eigenstate thermalization hypothesis (ETH) explains how closed quantum systems thermalize, with off-diagonal matrix elements—described by a smooth spectral function—governing relaxation dynamics. [Çeven et al., PRB 113, 045126 (2026)] proposed a hiearchy between the Thouless freqeuncy (set by transport) and the random-matrix-theory (RMT) frequency (set by spectral statistics) in a disordered spin-1/2 XX ladder, but without directly connecting it to the ETH framework. Here, we try to bridge this gap by analyzing the frequency dependence of the off-diagonal smooth spectral function. From our preliminary results, we find that a low-frequency plateau develops near the RMT frequency, while the Thouless freqeuncies lie at larger frequencies where the spectral function is already decaying. Our preliminary results link the hierarchy of relaxation timescales to the ETH structure underlying thermlzation in chaotic quantum systems.

Speaker: Kadir Çeven (Georg-August-Universität Göttingen)

10:15 Coffee Break

FOR Talks

20 Symmetry re-breaking in an effective theory of quantum coarsening

We present a simple theory accounting for two central observations in a recent experiment on quantum coarsening and collective dynamics on a programmable quantum simulator [T. Manovitz et al., Nature 638, 86 (2025)]: an apparent speeding up of the coarsening process as the phase transition is approached; and persistent oscillations of the order parameter after quenches within the ordered phase. Our theory, based on the Hamiltonian structure of the equations of motion in the classical limit of the quantum model, finds a speeding up already deep within the ordered phase, with subsequent slowing down as the domain wall tension vanishes upon approaching the critical line. Further, the oscillations are captured within a mean-field treatment of the order parameter field. For quenches within the ordered phase, small spatially-varying fluctuations in the initial mean-field lead to a remarkable long-time effect, wherein the system dynamically destroys its long-range order and has to coarsen to re-establish it. We term this phenomenon symmetry re-breaking, as the resulting late-time magnetization can have a sign opposite to the initial magnetization.

Speaker: Federico Balducci (MPI PKS)

21 E1 update

In this talk, we present our recent advances in project E1. In particular, we showcase our newly installed "magic" lattice with reduced spacing, which enhances cooperative light-matter interactions while reducing systematic heating. We report on our work towards the observation of subradiant excitations in a near-unity filled array of atomic dipoles. In the end, we will also provide an outlook on additional upgrades to the experimental apparatus, including a freely programmable lattice that would enable doublon-resolved imaging.

Speaker: Daniel Adler (MGQO)

22 Entanglement dynamics in chaotic systems from Ruelle-Pollicoit resonance

In chaotic quantum many-body systems, it was shown that the relaxation timescales of correlation functions can be encoded as quantum Ruelle–Pollicott (RP) resonances. They can arise as the leading eigenvalues of a propagator truncated to short-ranged operators, with the insight that short-ranged operators govern local thermalization. In this work, we extend RP resonances to the relaxation of Rényi entropies, closely related to the entanglement membrane picture. These RP resonances arise as leading eigenvalues of a higher-copy propagator, truncated to dressed domain walls between the effective degrees of freedom of the entanglement membrane. Focusing on translationally invariant Floquet brickwall circuits, we show that the RP resonance of the two-copy propagator governs the growth rate of the second Rényi entropy. By analyzing momentum-resolved propagators, we extract the membrane tension, which satisfies the expected universal constraints.

Speaker: Yahui Li (Technische Universität München)