报告题目：Understanding Hall effect in interacting systems with an atom-based quantum simulator

报 告 人：Tianwei Zhou, Department of Physics and Astronomy, University of Florence

报告时间：2025年9月2日16：00

报告地点：物理楼W105

内容摘要：Despite being of one of the most fundamental phenomena in solid-state physics, a comprehension of the Hall effect remains challenging whenever interactions are present among the carriers. I will report on the first quantum simulation of the Hall effect for strongly interacting fermions [1]. By performing direct measurements of current and charge polarization in an ultracold-atom simulator, we trace the buildup of the Hall response in a synthetic ladder pierced by a magnetic flux through controllable quench dynamics. We unveil a universal interaction-independent behavior above an interaction threshold, where the Hall response deviates significantly from that expected for a non-interacting electron gas, approaching a universal value [2]. Our system, able to reach hard-to-compute regimes also demonstrates the power of quantum simulation to describe strongly correlated topological states of matter.

The quantum simulation of the Hall effect with ultracold atoms subjected to artificial magnetic fields opened up a path to gain new insight into the physics of interacting Hall systems, but the Hall resistance associated with the transverse transport in strongly correlated systems and often interpreted as a measure of the inverse carrier density, has only been observed in electronic systems so far. I will report on a direct measurement of the Hall voltage and of the Hall resistance in a neutral system, where we demonstrate a novel technique for the measurement of the Hall voltage in a neutral-atom-based quantum simulator [3,4]. From that we provide the first direct measurement of the Hall resistance in a cold-atom analogue of a solid-state Hall bar and study its dependence on the carrier density, along with theoretical analyses. Our work closes a major gap between analog quantum simulations and actual measurements performed in real solid-state systems.

As a prospect, I will briefly talk about the ongoing measurements of chiral edge currents under strong interactions at unitary filling, and the feasibility to observe the Hall response on a triangular ladder.

参考文献：

[1] T.-W. Zhou et al., Science 381, 427 (2023)

[2] S. Greschner et al., Phys. Rev. Lett. 122, 083402 (2019)

[3] T.-W. Zhou et al., arXiv:2411.09744

[4] M. Buser et al., Phys. Rev. Lett. 126, 030501 (2021)