Exploring the Kibble-Zurek mechanism with homogeneous Bose gases

TL;DR

This paper reviews experiments on temperature quenches across Bose-Einstein condensation transitions in homogeneous ultracold gases, providing insights into the Kibble-Zurek mechanism, including scaling laws, topological defects, and critical exponents.

Contribution

It presents a comprehensive experimental investigation of the Kibble-Zurek mechanism in homogeneous Bose gases, confirming theoretical predictions and measuring critical exponents.

Findings

Confirmation of Kibble-Zurek scaling laws

Direct evidence of the 'freeze-out' hypothesis

Measurement of critical exponents for BEC transition

Abstract

Out-of-equilibrium phenomena is a subject of considerable interest in many fields of physics. Ultracold quantum gases, which are extremely clean, well-isolated and highly controllable systems, offer ideal platforms to investigate this topic. The recent progress in tailoring trapping potentials now allows the experimental production of homogeneous samples in custom geometries, which is a key advance for studies of the emergence of coherence in interacting quantum systems. Here we review recent experiments in which temperature quenches have been performed across the Bose-Einstein condensation (BEC) phase transition in an annular geometry and in homogeneous 3D and quasi-2D gases. Combined, these experiments give a comprehensive picture of the Kibble-Zurek (KZ) scenario through complementary measurements of correlation functions and topological defects density. They also allow the measurement of KZ scaling laws, the direct confirmation of the "freeze-out" hypothesis that underlies the KZ theory, and the extraction of critical exponents of the Bose-Einstein condensation transition.