Many-Body Dissipative Flow of a Confined Scalar Bose-Einstein Condensate Driven by a Gaussian Impurity

TL;DR

This study explores how a Gaussian impurity moving within a cigar-shaped Bose-Einstein condensate induces dissipative flow, revealing a transition from superfluidity to dissipation characterized by gray soliton emission and decay.

Contribution

It provides new insights into the dissipative dynamics and soliton formation in driven Bose-Einstein condensates, highlighting the dependence on driving frequency, obstacle characteristics, and interaction strength.

Findings

Superfluid phase persists at very small and large driving frequencies.

Dissipation occurs at intermediate frequencies with gray soliton emission.

Single-shot images reveal soliton decay and splitting in large particle number regimes.

Abstract

The many-body dissipative flow induced by a mobile aussian impurity harmonically oscillating within a cigar-shaped Bose-Einstein condensate is investigated. For very {small and large driving frequencies} the superfluid phase is preserved. Dissipation is identified, for intermediate driving frequencies, by the non-zero value of the drag force whose abrupt increase {signals the spontaneous downstream emission of an array of gray solitons. After each emission event, typically each of the solitary waves formed decays and splits into two daughter gray solitary waves that are found to be robust propagating in the bosonic background for large evolution times.} In particular, a smooth transition towards dissipation is observed, with the {\it critical} velocity for solitary wave formation depending on both the characteristics of the obstacle, namely its driving frequency and width as well as on the interaction strength. The variance of a sample of single-shot simulations indicates the fragmented nature of the system; here it is found to increase during evolution for driving frequencies where the coherent structure formation becomes significant. Finally, we demonstrate that for fairly large particle numbers in-situ single-shot images directly capture the gray soliton's decay and splitting.