Dissipative Transport of a Bose-Einstein Condensate

TL;DR

This paper studies how impurities affect the damping of collective motion in a Bose-Einstein condensate, revealing universal damping behavior and soliton-driven fragmentation.

Contribution

It introduces a detailed analysis of impurity-induced damping in BECs, highlighting universal scaling laws and the role of dark solitons in condensate fragmentation.

Findings

Damping rate depends on impurity strength, velocity, and interactions.

Universal damping behavior in the Thomas-Fermi regime.

Fragmentation driven by dark soliton formation.

Abstract

We investigate the effects of impurities, either correlated disorder or a single Gaussian defect, on the collective dipole motion of a Bose-Einstein condensate of $^7$Li in an optical trap. We find that this motion is damped at a rate dependent on the impurity strength, condensate center-of-mass velocity, and interatomic interactions. Damping in the Thomas-Fermi regime depends universally on the disordered potential strength scaled to the condensate chemical potential and the condensate velocity scaled to the peak speed of sound. The damping rate is comparatively small in the weakly interacting regime, and the damping in this case is accompanied by strong condensate fragmentation. \textit{In situ} and time-of-flight images of the atomic cloud provide evidence that this fragmentation is driven by dark soliton formation.