Quantum simulation of a lattice gauge theory: thermalization, many-body scars, and collision dynamics

Abstract: Gauge theories form the foundation of modern physics, with applications ranging from early-universe cosmology and heavy-ion collisions to condensed matter systems. However, simulating the real-time dynamics of such quantum many-body systems on classical computers is fraught with difficulties, motivating the pursuit of alternative venues. I will present recent experiments where we employ a large-scale Bose-Hubbard quantum simulator to emulate a U(1) lattice gauge theory, which couples charged matter fields through dynamical gauge fields. In the wake of a global quench that brings the system far from equilibrium, we observe the relaxation dynamics and the emergence of thermodynamic description, the irreversible behavior from an underlying reversible unitary time evolution. Tuning to different quench protocols, we explore the slowed thermalization through quantum many-body scarring, which deters the scrambling of information. This is demonstrated by the slowed entropy growth measured using the Hong-Ou-Mandel interference with an optical superlattice. We further demonstrate such a quantum simulator can be used to investigate confinement physics and even simulate particle collision dynamics. Our work paves the way for the exploration of more complex, higher-dimensional gauge theories using state-of-the-art quantum technology.