Vortex dipoles in expanding shell-shaped Bose-Einstein condensates

Abstract

Releasing shell-shaped Bose-Einstein condensates from the external confinement produces a spherically symmetric density distribution characterized by concentric ripples surrounding a central peak. Here we investigate how a vortex-antivortex dipole affects this dynamics, finding that increasing dipole separation progressively breaks the spherical symmetry. Correspondingly, the interplay of vortex physics and curvature produces a nonmonotonic behavior of the cloud aspect ratio with the vortex distance, and decreases the maximal central density achieved during the expansion. These features can be used for detecting vortex dipoles prepared in shell-shaped superfluids, as well as a basis for analyzing their signatures in other thin superfluids with more general curved geometries.

8 pages, 6 figures; including supplemental material