Quasi-universal transient behavior of a nonequilibrium Mott insulator driven by an electric field

TL;DR

This paper investigates the nonequilibrium dynamics of a driven Mott insulator using a strong-coupling expansion, revealing a long-lived transient prethermalized state with quasi-universal behavior and conditions for rapid thermalization.

Contribution

It introduces a self-consistent strong-coupling approach to describe nonequilibrium behavior in the Fermi-Hubbard model, highlighting the existence of a long-lived transient state and its properties.

Findings

Transient prethermalized state persists over broad field strengths.

Damping of Bloch oscillations depends on electric field direction.

Rapid thermalization occurs when field strength equals interaction energy.

Abstract

We use a self-consistent strong-coupling expansion for the self-energy (perturbation theory in the hopping) to describe the nonequilibrium dynamics of strongly correlated lattice fermions. We study the three-dimensional homogeneous Fermi-Hubbard model driven by an external electric field showing that the damping of the ensuing Bloch oscillations depends on the direction of the field, and that for a broad range of field strengths, a long-lived transient prethermalized state emerges. This long-lived transient regime implies that thermal equilibrium may be out of reach of the time scales accessible in present cold atom experiments, but shows that an interesting new quasi-universal transient state exists in nonequilibrium governed by a thermalized kinetic energy but not a thermalized potential energy. In addition, when the field strength is equal in magnitude to the interaction between atoms, the system undergoes a rapid thermalization, characterized by a different quasi-universal behavior of the current and spectral function for different values of the hopping.