Formation of local and global currents in a toroidal Bose--Einstein condensate via an inhomogeneous artificial gauge field

TL;DR

This paper investigates how an inhomogeneous artificial gauge field influences local and global currents in a Bose--Einstein condensate confined in ring geometries, revealing quantized and linear angular momentum regimes.

Contribution

It demonstrates the formation of local vortices and global currents induced by inhomogeneous gauge fields in ring-shaped Bose--Einstein condensates, highlighting different angular momentum behaviors.

Findings

Quantized angular momentum increase for weak gauge fields

Linear, non-quantized angular momentum for strong gauge fields

Characterization of angular momentum in asymmetric traps

Abstract

We study the effects of a position-dependent artificial gauge field on an atomic Bose--Einstein condensate in quasi-one-dimensional and two-dimensional ring settings. The inhomogeneous artificial gauge field can induce global and local currents in the Bose--Einstein condensate via phase gradients along the ring and vortices, respectively. We observe two different regimes in the system depending on the radial size of the ring and strength of the gauge field. For weak artificial gauge fields, the angular momentum increases, as expected, in a quantized manner; however, for stronger values of the fields, the angular momentum exhibits a linear (non-quantized) behavior. We also characterize the angular momentum for non-cylindrically symmetric traps.