Vortices in attractive Bose-Einstein condensates in two dimensions

TL;DR

This paper investigates the structure and stability of quantum vortices in two-dimensional attractive Bose-Einstein condensates, revealing new radially excited states and stability regimes that could be observed experimentally.

Contribution

It introduces a detailed analysis of vortex states as ring bright solitons and identifies radially excited states unique to attractive condensates, extending the understanding of their stability.

Findings

Vortices appear as ring bright solitons with nonzero winding number.

An infinite sequence of radially excited states exists for each vortex.

Stable and unstable regimes can be achieved in confined geometries.

Abstract

The form and stability of quantum vortices in Bose-Einstein condensates with attractive atomic interactions is elucidated. They appear as ring bright solitons, and are a generalization of the Townes soliton to nonzero winding number $m$. An infinite sequence of radially excited stationary states appear for each value of $m$, which are characterized by concentric matter-wave rings separated by nodes, in contrast to repulsive condensates, where no such set of states exists. It is shown that robustly stable as well as unstable regimes may be achieved in confined geometries, thereby suggesting that vortices and their radial excited states can be observed in experiments on attractive condensates in two dimensions.