Vortex scattering by impurities in a Bose-Einstein condensate

TL;DR

This paper investigates how vortex-antivortex pairs in a 2D Bose-Einstein condensate interact with density impurities, distinguishing effects caused by velocity fields and density inhomogeneities.

Contribution

It provides a detailed analysis of vortex-impurity interactions, clarifying the roles of velocity and density effects in vortex dynamics within BECs.

Findings

Vortex-antivortex pairs exhibit different scattering behaviors depending on impurity characteristics.

Density impurities can mimic vortex profiles without circulation, affecting vortex trajectories.

The study identifies qualitative scenarios of vortex-impurity interactions in BECs.

Abstract

Understanding quantum dynamics in a two-dimensional Bose-Einstein condensate (BEC) relies on understanding how vortices interact with each others microscopically and with local imperfections of the potential which confines the condensate. Within a system consisting of many vortices, the trajectory of a vortex-antivortex pair is often scattered by a third vortex, an effect previously characterised. However, the natural question remains as to how much of this effect is due to the velocity induced by this third vortex and how much is due to the density inhomogeneity which it introduces. In this work, we describe the various qualitative scenarios which occur when a vortex-antivortex pair interacts with a smooth density impurity whose profile is identical to that of a vortex but lacks the circulation around it.