Formation of Bose-Einstein condensates

TL;DR

This paper reviews the understanding of Bose-Einstein condensate formation from thermal gases, highlighting experimental and theoretical progress, the role of topological defects, and connections to universal nonequilibrium phase transition phenomena.

Contribution

It provides a comprehensive overview of recent advances in understanding BEC formation, including experimental verification of the Kibble-Zurek mechanism and open questions in quantum phase transition dynamics.

Findings

Verification of the Kibble-Zurek mechanism in cold-atom experiments

Observation of topological defect formation during quenched phase transitions

Progress in connecting BEC dynamics to universal critical phenomena

Abstract

The problem of understanding how a coherent, macroscopic Bose-Einstein condensate (BEC) emerges from the cooling of a thermal Bose gas has attracted significant theoretical and experimental interest over several decades. The pioneering achievement of BEC in weakly-interacting dilute atomic gases in 1995 was followed by a number of experimental studies examining the growth of the BEC number, as well as the development of its coherence. More recently there has been interest in connecting such experiments to universal aspects of nonequilibrium phase transitions, in terms of both static and dynamical critical exponents. Here, the spontaneous formation of topological structures such as vortices and solitons in quenched cold-atom experiments has enabled the verification of the Kibble-Zurek mechanism predicting the density of topological defects in continuous phase transitions, first proposed in the context of the evolution of the early universe. This chapter reviews progress in the understanding of BEC formation, and discusses open questions and future research directions in the dynamics of phase transitions in quantum gases.