Kibble-Zurek scaling and its breakdown for spontaneous generation of Josephson vortices in Bose-Einstein condensates

TL;DR

This paper investigates the formation of Josephson vortices in Bose-Einstein condensates during rapid cooling, confirming the Kibble-Zurek mechanism for fast quenches and exploring its breakdown for slower quenches through simulations.

Contribution

It provides the first direct test of Kibble-Zurek scaling laws in Bose-Einstein condensates using Josephson vortices in a dual-ring trap geometry.

Findings

Fast quenches follow a -1/4 power-law scaling of defect number.

Slower quenches deviate from Kibble-Zurek scaling due to vortex stability.

Interference measurements enable long-time observation of defects.

Abstract

Atomic Bose-Einstein condensates confined to a dual-ring trap support Josephson vortices as topologically stable defects in the relative phase. We propose a test of the scaling laws for defect formation by quenching a Bose gas to degeneracy in this geometry. Stochastic Gross-Pitaevskii simulations reveal a -1/4 power-law scaling of defect number with quench time for fast quenches, consistent with the Kibble-Zurek mechanism. Slow quenches show stronger quench-time dependence that is explained by the stability properties of Josephson vortices, revealing the boundary of the Kibble-Zurek regime. Interference of the two atomic fields enables clear long-time measurement of stable defects, and a direct test of the Kibble-Zurek mechanism in Bose-Einstein condensation.