18.02.2026 João C. Pinto Barros (ETH Zurich)
Location: HIT E 41.1, Time: 12:00
When Thermalization Fails: What Long-Time Dynamics can Reveal about Lattice Gauge Theories
Gauge symmetry is often described as “not a true symmetry,” but rather as a “redundancy in the description of physical degrees of freedom”. In this talk, I will introduce lattice gauge theories and discuss how this viewpoint can be re-examined from the perspective of near-term quantum simulators.
I will then turn to the long-time behavior of lattice gauge theories, focusing on the breakdown of thermalization due to the presence of atypical high-energy, low-entanglement eigenstates often dubbed Quantum Many-Body Scars. These non-thermal states can strongly influence real-time dynamics and lead to persistent memory of initial conditions. I will argue that such dynamical signatures provide a new window into the microscopic structure of lattice theories, with direct relevance for their realization and diagnosis in future quantum simulation platforms.
25.02.2026 Rishabh Gvalani (ETH Zurich)
Location: HIT E 41.1, Time: 12:00
Noise in fluid dynamics
I will provide a brief introduction to the phenomenon of turbulence in fluid flows and how models of fluids with random forcing can be used to study certain universal scaling properties of turbulent fluids. I will conclude by describing a few rigorous results in the setting of passive scalar turbulence.
05.03.2026 Zhiyang (Paul) Zeng (MPSD Hamburg and University of Oxford)
Location: HIT E 41.1, Time: 12:00
Alter-chiral systems: a new landscape for chirality engineering
Chirality is a fundamental symmetry property of materials, underpinning a wide range of optical, electronic and transport phenomena. Beyond the conventional classification of crystal systems as chiral or achiral, there exists a distinct subclass of achiral systems known as anti-ferrochiral, which provide an ideal platform for realizing chiral responses in otherwise achiral crystals. I will focus on two recent experimental demonstrations: ultrafast optical control of chirality and strain control of chirality.
Following these examples, the concept of higher-order chirality—tentatively termed alter-chirality—will be introduced as a unifying symmetry framework for describing and classifying these phenomena. Within this framework, I will discuss further novel properties based on symmetry arguments, including linear and nonlinear responses, as well as quasiparticle excitations.
References
[1] A. B. Harris, R. D. Kamien, and T. C. Lubensky, Rev. Mod. Phys. 71, 1745 (1999).
[2] Z. Zeng et al., Science 387, 431 (2025).
[3] Z. Zeng et al., “The Piezochiral Effect,” arXiv:2510.21674 (2025).
11.03.2026 Andrew Jreissaty and Tommaso Bonaccorsi (ETH Zurich)
Location: HIT E 41.1, Time: 12:00
Machine learning superfluid entropy transport for strongly interacting fermionic systems
In this talk, Tommaso and I (Andrew) will discuss the ongoing collaboration between our respective groups (special shout-out to Yaakov Yudkin, Myles Huang and Jannes Nys as well) to create a machine-learning based digital twin of an experimental quantum gas simulator for strongly interacting superfluid fermions at unitarity and beyond. We will introduce the relevant physics (based on https://arxiv.org/pdf/2309.04359) and discuss the tools that we have been using (principal component analysis, neural ODEs and more) to better understand and simulate the transport dynamics of these systems.
25.03.2026 Adrián Pérez-Salinas (ETH Zurich)
Location: HIT E 41.1, Time: 12:00
The subtleties of sampling hardness in quantum systems
Sampling tasks have been successful in establishing quantum advantages both in theory and experiments. This has fueled the use of quantum computers for generative modeling to create samples following the probability distribution underlying a given dataset. In particular, the potential to build generative models on classically hard distributions would immediately preclude classical simulability, due to theoretical separations. In this talk, we will review the foundations of sampling hardness and investigate its consequences. We will visit quantum generative models from the perspective of output distributions, showing that models that anticoncentrate are not trainable on average, including those exhibiting quantum advantage. This observed trade-off is linked to verification of quantum processes. In addition, this phenomenon prevents the use of classical simulation for physical processes that require sampling from a large space for their computation (WIP). In contrast, quantum processes sparse output distributions and much more manageable, and still compatible with quantum-classical separations.
01.04.2026 Arthur Christianen (ETH Zurich)
Location: HIT E 41.1, Time: 12:00
Few-Body Physics in a Many-Body World
A central challenge in quantum physics is understanding how complex, emergent behavior arises from the interactions of systems’ microscopic constituents. A bottom-up route toward gaining insight is provided by studying the quantum impurity scenario, in which a single particle is immersed in a quantum environment. The impurity becomes a dressed quasiparticle called a polaron, whose interactions and binding with the bath particles reveal the rich interplay between few- and many-body phenomena.
In this talk, I will explore three interrelated questions: How does few-body binding change in a quantum-degenerate environment? Or conversely, how do few-body correlations affect the phase diagram of quantum mixtures? And how can impurity-bath interactions be used to detect and characterize correlated quantum states? I will establish how these questions naturally emerge across diverse experimental platforms, from ultracold atomic and molecular gases to two-dimensional semiconductors. In these systems, polarons can help us understand open questions about correlated phases such as unconventional superfluids and Wigner crystals, and manifest surprising behavior, such as exotic molecular states in superpositions of different particle numbers.
Altogether, these examples show how few-body physics provides a powerful lens to understand and probe emergent phenomena in strongly correlated quantum systems.
08.04.2026 Glenn Wagner (ETH Zurich)
Location: HIT E 41.1, Time: 12:00
The Wonders of Moiré Materials
Moiré materials offer a tunable platform for studying strongly correlated states of matter. The most commonly realized moiré materials consist of two dimensional lattices stacked on top of one another and twisted. The most prominent example is twisted bilayer graphene, which exhibits unconventional superconductivity, linear-in-T resistivity and a quantized anomalous Hall effect. More recently, attention has focused on twisted MoTe2 which hosts fractional Chern insulators, marking the first time this phase has been observed at zero magnetic field.
In this talk I will explain what makes moiré materials so interesting and illustrate this with three examples: (1) In the quantum anomalous Hall regime of twisted bilayer graphene, the interplay of topology and correlations gives rise to an energetic competition between different types of domain walls. (2) The correlated insulators of twisted bilayer graphene have a pseudospin spiral structure that gives rise to moiré scale modulations of a graphene scale bond order. (3) Pseudospin skyrmions can be energetically favourable, offering a potential mechanism for superconductivity.
15.04.2026 Nina Bielinski (ETH Zurich)
Location: HIT E 41.1, Time: 12:00
Floquet and Photoemission: Optical control of the Dirac gap in a topological antiferromagnet
Floquet-Bloch engineering, achieved via time periodic driving of a material, can modify the electronic and magnetic phases in a solid through effective manipulation of the electronic bands. Despite the promise of optically-driven Floquet-Bloch manipulation as a highly tunable means to engineer band structures, experimental realizations of this technique remain scarce. In this talk I will discuss how we used time- and angle-resolved photoemission spectroscopy to realize Floquet-Bloch manipulation of the Dirac surface-state mass of the topological antiferromagnet MnBi2Te4. We observed that using opposite helicities of mid-infrared circularly polarized light results in substantially different Dirac mass gaps exclusively when the system is the antiferromagnetic phase. These results demonstrate Floquet-Bloch engineering as a powerful tool for controlling topology, and for uncovering properties of materials that may elude conventional probes.