Matter-wave dark solitons in box-like traps

TL;DR

This paper investigates the dynamics of dark solitons in box-like Bose-Einstein condensate traps, focusing on energy dissipation during wall reflections and the eventual stabilization of soliton motion.

Contribution

It provides a numerical analysis of dark soliton behavior in box traps with different wall profiles, highlighting energy loss mechanisms and stabilization effects.

Findings

Solitons dissipate energy during wall reflections via sound emission.

Energy loss depends on the wall's shape and parameters.

Solitons eventually stabilize after multiple reflections.

Abstract

Motivated by the experimental development of quasi-homogeneous Bose-Einstein condensates confined in box-like traps, we study numerically the dynamics of dark solitons in such traps at zero temperature. We consider the cases where the side walls of the box potential rise either as a power-law or a Gaussian. While the soliton propagates through the homogeneous interior of the box without dissipation, it typically dissipates energy during a reflection from a wall through the emission of sound waves, causing a slight increase in the soliton's speed. We characterise this energy loss as a function of the wall parameters. Moreover, over multiple oscillations and reflections in the box-like trap, the energy loss and speed increase of the soliton can be significant, although the decay eventually becomes stabilized when the soliton equilibrates with the ambient sound field.