Generating, dragging and releasing dark solitons in elongated Bose-Einstein condensates

TL;DR

This paper presents a theoretical method to generate, manipulate, and release dark solitons in elongated Bose-Einstein condensates using moving defect potentials, with robustness and stability analyzed through simulations and linear stability analysis.

Contribution

It introduces a robust protocol for creating and controlling dark solitons via moving defects, including multiple defect strategies for complex soliton dynamics.

Findings

Successful nucleation and pinning of dark solitons by moving defects.

Robustness of the generation protocol across parameter variations.

Identification of dynamical instabilities during long-term soliton holding.

Abstract

We theoretically analyze quasi-one-dimensional Bose-Einstein condensates under the influence of a harmonic trap and a narrow potential defect that moves through the atomic cloud. Performing simulations on the mean field level, we explore a robust mechanism in which a single dark soliton is nucleated and immediately pinned by the moving defect, making it possible to drag it to a desired position and release it there. We argue on a perturbative level that a defect potential which is attractive to the atoms is suitable for holding and moving dark solitons. The soliton generation protocol is investigated over a wide range of model parameters and its success is systematically quantified by a suitable fidelity measure, demonstrating its robustness against parameter variations, but also the need for tight focusing of the defect potential. Holding the soliton at a stationary defect for long times may give rise to dynamical instabilities, whose origin we explore within a Bogoliubov-de Gennes linearization analysis. We show that iterating the generation process with multiple defects offers a perspective for initializing multiple soliton dynamics with freely chosen initial conditions.