Quantum Simulation of Non-equilibrium Dynamics and Thermalization of the Schwinger Model

Quantum computing has drawn significant interest from the nuclear and particle physics community since it may provide a method to overcome the notorious sign problem when one tries to numerically compute observables on a lattice. With the NISQ era coming, we expect to see wide applications of the quantum computing in the understanding of the real time dynamics of the quantum field theory in vacuum and at finite temperature. For such applications at finite temperature, it is essential to prepare an initial thermal state efficiently, which is not an easy task.

Motivated by this, we consider a quantum field theory coupled with a thermal environment and study the non-unitary time evolution of the field theory. In particular, I will discuss the 1+1 dimensional U(1) gauge theory, also known as the Schwinger model, coupled with a thermal scalar field. The non-equilibrium dynamics of the Schwinger model is governed by a Lindblad equation in the limit of quantum Brownian motion, which drives the Schwinger model into thermal equilibrium. I will explain how to simulate the non-equilibrium dynamics and thermalization on a quantum computer and present results from both the IBM quantum simulators and devices.