Quench dynamics of the Schwinger model via variational quantum algorithms
Lento Nagano, Aniruddha Bapat, C. Bauer
Abstract
We investigate the real-time dynamics of the ($1+1$)-dimensional U(1) gauge theory known as the Schwinger model via variational quantum algorithms. Specifically, we simulate quench dynamics in the presence of an external electric field. First, we use a variational quantum eigensolver to obtain the ground state of the system in the absence of an external field. With this as the initial state, we perform real-time evolution under an external field via a fixed-depth, parameterized circuit whose parameters are updated using McLachlan's variational principle. We use the same ansatz for initial-state preparation and time evolution, by which we are able to reduce the overall circuit depth. We test our method with a classical simulator and confirm that the results agree well with exact diagonalization.