Weakly interacting disordered Bose gases out of equilibrium: from multiple scattering to superfluidity

TL;DR

This paper investigates the out-of-equilibrium dynamics of a disordered Bose gas, revealing two regimes: one dominated by multiple scattering with short-range coherence, and another resembling superfluidity with long-range order.

Contribution

It identifies and characterizes two distinct out-of-equilibrium regimes in disordered Bose gases based on the relative strength of interactions and disorder.

Findings

Short-range coherence in the disorder-dominated regime.

Emergence of long-range algebraic coherence in the superfluid regime.

Transition from multiple scattering to superfluid-like behavior.

Abstract

We explore the quench dynamics of a two-dimensional, weakly interacting disordered Bose gas for various relative strengths of interactions and disorder. This allows us to identify two well distinct out-of-equilibrium regimes. When interactions are smaller than the disorder, the gas experiences multiple scattering and exhibits a short-range spatial coherence. At short time this coherence is only smoothly affected by interactions, via a diffusion process of the particles' energies. When interactions are larger than the disorder, scattering ceases and the gas behaves more and more like a fluid, ultimately like a superfluid at low energy. In the superfluid regime, the gas exhibits a long-range algebraic coherence, characteristic of a pre-thermal regime in disorder.