Dark soliton decay due to trap anharmonicity in atomic Bose-Einstein condensates

TL;DR

This paper investigates how trap anharmonicities in atomic Bose-Einstein condensates cause dark soliton decay by disrupting soliton-sound equilibrium, suggesting experimental modifications to observe this decay.

Contribution

It reveals that trap anharmonicities lead to rapid dark soliton decay, highlighting a new decay mechanism in Bose-Einstein condensates not previously emphasized.

Findings

Anharmonic trap potentials destabilize dark solitons.

Soliton decay occurs faster with anharmonicities than other mechanisms.

Proposed experimental modifications can observe this decay channel.

Abstract

A number of recent experiments with nearly pure atomic Bose-Einstein condensates have confirmed the predicted dark soliton oscillations when under harmonic trapping. However, a dark soliton propagating in an inhomogeneous condensate has also been predicted to be unstable to the emission of sound waves. Although harmonic trapping supports an equilibrium between the co-existing soliton and sound, we show that the ensuing dynamics are sensitive to trap anharmonicities. Such anharmonicities can break the soliton-sound equilibrium and lead to the net decay of the soliton on a considerably shorter timescale than other dissipation mechanisms. Thus, we propose how small realistic modifications to existing experimental set-ups could enable the experimental observation of this decay channel.