Ground-State Properties for Coupled Bose-Einstein Condensates inside a Cavity Quantum Electrodynamics

TL;DR

This paper analytically explores the ground-state properties and quantum phase transition of two-component Bose-Einstein condensates in a cavity QED system, highlighting controllable interatomic interactions and observable signatures of phase change.

Contribution

It introduces a generalized Dicke model with quadratic interatomic interactions and predicts a zero-temperature quantum phase transition in a cavity QED setup.

Findings

Identification of a quantum phase transition from normal to superradiant phases.

Control of interatomic interactions via Feshbach resonance.

Observable photon signatures of the phase transition.

Abstract

We analytically investigate the ground-state properties of two-component Bose-Einstein condensates with few ⁸⁷Rb atoms inside a high-quality cavity quantum electrodynamics. In the SU(2) representation for atom, this quantum system can be realized a generalized Dicke model with a quadratic term arising from the interatomic interactions, which can be controlled experimentally by Feshbach resonance technique. Moreover, this weak interspecies interaction can give rise to an important zero-temperature quantum phase transition from the normal to the superradiant phases, where the atomic ensemble in the normal phase is collectively unexcited while is macroscopically excited with coherent radiations in the superradiant phase. Finally, we propose to observe this predicted quantum phase transition by measuring the direct and striking signatures of the photon field in terms of a heterodyne detector out of the cavity.