Thermalization of matter waves in speckle potentials

TL;DR

This paper demonstrates that nonlinear matter waves in speckle potentials thermalize to a universal distribution, with the emergence of a condensate at low disorder levels, revealing new insights into wave thermalization and phase transitions.

Contribution

It introduces the concept of thermalization of nonlinear matter waves in speckle potentials and uncovers the formation of a condensate at low disorder, a novel phenomenon in this context.

Findings

Matter waves reach a universal Rayleigh-Jeans distribution after evolution.

A condensate forms at low disorder strengths in the equilibrium state.

The phase diagram of the equilibrated wave reveals new phase transition behavior.

Abstract

We show that the momentum distribution of a nonlinear matter wave suddenly released with a finite velocity in a speckle potential converges, after an out-of-equilibrium evolution, to a universal Rayleigh-Jeans thermal distribution. By exploring the complete phase diagram of the equilibrated wave, we discover that for low but nonzero values of the disorder strength, a large-scale structure -a condensate- appears in the equilibrium distribution.