Inhomogeneous Kibble-Zurek mechanism: vortex nucleation during Bose-Einstein condensation

TL;DR

This paper investigates how confinement in a trapped gas affects vortex formation during Bose-Einstein condensation, revealing conditions under which vortex nucleation is suppressed or altered by the trap geometry and quench rate.

Contribution

It extends the Kibble-Zurek mechanism to inhomogeneous, trapped gases, showing how confinement influences vortex nucleation and scaling laws during BEC.

Findings

Vortex nucleation can be suppressed by the trap when the front speed is below a threshold.

Different scaling laws for vortex density depend on trap geometry and quench rate.

In toroidal traps, unique vortex formation behaviors are observed.

Abstract

The Kibble-Zurek mechanism is applied to the spontaneous formation of vortices in a harmonically trapped thermal gas following a temperature quench through the critical value for Bose-Einstein condensation. While in the homogeneous scenario vortex nucleation is always expected, we show that it can be completely suppressed in the presence of the confinement potential, whenever the speed of the spatial front undergoing condensation is lower than a threshold velocity. Otherwise, the interplay between the geometry and causality leads to different scaling laws for the density of vortices as a function of the quench rate, as we also illustrate for the case of a toroidal trapping potential.