Quench dynamics of a weakly interacting disordered Bose gas in momentum space

TL;DR

This paper investigates how weak interactions affect the out-of-equilibrium momentum space dynamics of a disordered Bose gas, revealing that interactions lead to thermalization and suppression of coherent backscattering.

Contribution

It introduces a diagrammatic quantum transport theory to describe the thermalization process and the destruction of coherent backscattering in an interacting disordered Bose gas.

Findings

Interactions cause exponential relaxation of coherent backscattering.

Thermalization couples diffusive and coherent components.

Numerical simulations confirm theoretical predictions.

Abstract

We theoretically study the out-of-equilibrium dynamics in momentum space of a weakly interacting disordered Bose gas launched with a finite velocity. In the absence of interactions, coherent multiple scattering gives rise to a background of diffusive particles, on top of which a coherent backscattering interference emerges. We revisit this scenario in the presence of interactions, using a diagrammatic quantum transport theory. We find that the dynamics is governed by coupled kinetic equations describing the thermalization of the diffusive and coherent components of the gas. This phenomenon leads to a destruction of coherent backscattering, well described by an exponential relaxation whose rate is controlled by the particle collision time. These predictions are confirmed by numerical simulations.