Creation and counting of defects in a temperature quenched Bose-Einstein Condensate

TL;DR

This paper investigates how defects form in a trapped ultracold Bose gas during temperature quenches across the BEC transition, revealing power-law defect scaling and saturation effects related to defect interactions.

Contribution

It demonstrates the scaling behavior of defect formation during BEC quenches and explains the saturation phenomenon at fast quench rates.

Findings

Power-law defect scaling for slow quenches

Saturation of defect number at fast quenches

Interactions among defects cause saturation

Abstract

We study the spontaneous formation of defects in the order parameter of a trapped ultracold bosonic gas while crossing the critical temperature for Bose-Einstein Condensation (BEC) at different rates. The system has the shape of an elongated ellipsoid, whose transverse width can be varied to explore dimensionality effects. For slow enough temperature quenches we find a power-law scaling of the average defect number with the quench rate, as predicted by the Kibble-Zurek mechanism. A breakdown of such a scaling is found for fast quenches, leading to a saturation of the average defect number. We suggest an explanation for this saturation in terms of the mutual interactions among defects.