Observation of universal Hall Response in strongly interacting fermions

Abstract - The Hall effect, which originates from the motion of charged particles in a magnetic field, has profound consequences for the description and characterization of materials, extending far beyond the original context of condensed matter physics. Although the Hall effect for non-interacting particles is well understood also in the quantum regime, understanding the Hall effect in interacting systems still represents a fundamental challenge even in the classical, weak-field case. Here we directly observe how the Hall response builds up in an interacting quantum system by exploiting controllable quench dynamics in an atomic quantum simulator. By tracking the motion of ultracold fermions in a synthetic ladder, we measure the Hall response depending on synthetic tunneling and atomic interactions, unveiling a universal behavior in the strongly interacting limit and exhibiting a clear agreement with theoretical analyses. We expect our findings to open new directions towards strongly correlated topological phases such as fractional quantum Hall states and spin liquids.