Small Numbers of Vortices in Anisotropic Traps

TL;DR

This paper studies how vortices form and arrange in rotating Bose-Einstein condensates with anisotropic traps, revealing a transition from lattice to linear vortex arrangements at a critical anisotropy.

Contribution

It introduces a variational method to determine critical stirring frequencies and vortex positions in anisotropic traps, highlighting a new linear vortex configuration.

Findings

Vortex positions shift from Abrikosov lattice to linear arrangements at critical anisotropy.

Critical stirring frequency for vortex formation is identified.

Small numbers of vortices exhibit predictable equilibrium positions.

Abstract

We investigate the appearance of vortices and vortex lattices in two-dimensional, anisotropic and rotating Bose-Einstein condensates. Once the anisotropy reaches a critical value, the positions of the vortex cores in the ground state are no longer given by an Abrikosov lattice geometry, but by a linear arrangement. Using a variational approach, we determine the critical stirring frequency for a single vortex as well as the equilibrium positions of a small number of vortices.