Exploring Symmetry Breaking at the Dicke Quantum Phase Transition

TL;DR

This paper investigates symmetry breaking phenomena at the Dicke quantum phase transition by coupling a Bose-Einstein condensate to an optical cavity, observing real-time symmetry breaking, phase distinction, and phase switching.

Contribution

It introduces real-time observation of symmetry breaking at the Dicke transition and explores the dynamics of phase switching and dependence on crossing rate.

Findings

Real-time detection of symmetry breaking.

Distinction between superradiant phases.

Demonstration of coherent phase switching.

Abstract

We study symmetry breaking at the Dicke quantum phase transition by coupling a motional degree of freedom of a Bose-Einstein condensate to the field of an optical cavity. Using an optical heterodyne detection scheme we observe symmetry breaking in real-time and distinguish the two superradiant phases. We explore the process of symmetry breaking in the presence of a small symmetry-breaking field, and study its dependence on the rate at which the critical point is crossed. Coherent switching between the two ordered phases is demonstrated.