Volume 80, Number 4, November 2007
Article Number 40004
Number of page(s) 5
Section General
Published online 24 October 2007
EPL, 80 (2007) 40004
DOI: 10.1209/0295-5075/80/40004

Ground-state properties for coupled Bose-Einstein condensates inside a cavity quantum electrodynamics

Gang Chen1, 2, 3, Zidong Chen1 and J.-Q. Liang3

1  Department of Physics, Shaoxing College of Arts and Sciences, Shaoxing 312000, PRC
2  Department of Physics, Zhejiang Normal University - Jinhua 321004, China
3  Institute of Theoretical Physics, Shanxi University - Taiyuan 030006, China

received 18 July 2007; accepted in final form 19 September 2007; published November 2007
published online 24 October 2007

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 an atom, this quantum system can be realized as a generalized Dicke model with a quadratic term arising from the interatomic interactions, which can be controlled experimentally by the 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 it 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.

03.75.Kk - Dynamic properties of condensates; collective and hydrodynamic excitations, superfluid flow.
42.50.Pq - Cavity quantum electrodynamics; micromasers.

© Europhysics Letters Association 2007