Issue
EPL
Volume 86, Number 4, May 2009
Article Number 44002
Number of page(s) 4
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
DOI http://dx.doi.org/10.1209/0295-5075/86/44002
Published online 26 May 2009
EPL, 86 (2009) 44002
DOI: 10.1209/0295-5075/86/44002

Interaction-induced topological quantum interference in an extended Dicke model

Gang Chen1, 2, Zheng-Yuan Xue3, L. F. Wei4 and J.-Q. Liang1

1   Institute of Theoretical Physics, Shanxi University - Taiyuan 030006, China
2   Department of Physics, Shaoxing College of Arts and Sciences - Shaoxing 312000, China
3   Department of Physics and Center of Theoretical and Computational Physics, The University of Hong Kong - Pokfulam Road, Hong Kong, China
4   Laboratory of Quantum Opt-electronics, Southwest Jiaotong University - Chengdu 610031, China

jqliang@sxu.edu.cn

received 28 February 2009; accepted in final form 23 April 2009; published May 2009
published online 26 May 2009

Abstract
In this paper we predict a topological quantum interference effect in an extended Dicke model with controllable long-range atom-atom interactions by means of coherent-state path integral. Due to the intrinsic competition between the atom-atom interactions and atom-field coupling, an interesting topological interference of the instanton and anti-instanton tunneling paths could occur. As a consequence, this model only with a few odd-number atoms has a twofold absolute degenerate ground-state subspace with a large energy gap, which becomes larger with the increasing of the system size. Therefore, the collective decoherence arising from noise in the external control parameters could be effectively suppressed in terms of adiabatic process between this absolute degenerate ground-state subspace associated with a finite energy gap.

PACS
42.50.Nn - Quantum optical phenomena in absorbing, amplifying, dispersive and conducting media: cooperative phenomena in quantum optical systems.

© EPLA 2009