Kibble-Zurek mechanism in the self-organization of a cold atomic cloud

TL;DR

This paper investigates the Kibble-Zurek mechanism in a cold atomic cloud, demonstrating how defect formation during phase transition follows a power-law related to sweep time, consistent with theoretical predictions.

Contribution

It provides experimental evidence of the Kibble-Zurek mechanism in a cold atomic system, linking defect density to transition crossing rate.

Findings

Defect number decreases as a power-law with sweep time

Measured exponent aligns with supercritical bifurcation predictions

Spontaneous pattern formation observed in atomic spins

Abstract

When applying two counter-propagating laser beams to a cold cloud of Rubidium atoms, we observe the spontaneous formation of intensity patterns associated with a spatial structuration of the atomic spins. We study the average number of defects in these patterns as a function of the sweep time employed to cross the transition threshold. We observe a power-law decrease of the number of defects with increasing sweep time, typical of the Kibble-Zurek mechanism. The measured exponent is consistent with the prediction for a supercritical bifurcation.