Interaction-induced topological quantum interference in an extended Dicke model

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

Corresponding author: jqliang@sxu.edu.cn

Received: 28 February 2009
Accepted: 23 April 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.