Eur. Phys. J. D (2012) 66: 90
https://doi.org/10.1140/epjd/e2012-20523-9

Regular Article

Dynamics of two-level systems beyond the rotating-wave approximation

¹ Department of Physics, Harbin Institute of Technology, Harbin 150001, P.R. China
² Department of Physics, Fuzhou University, Fuzhou 350002, P.R. China
³ School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, P.R. China

^a e-mail: jiesong2002@gmail.com

Received: 8 November 2011
Received in final form: 17 January 2012
Published online: 19 April 2012

Abstract

We study the dynamics of quantum discord and entanglement in a two-qubit system coupled to the same quantized field without rotating-wave approximation. In the absence of initial correlations, we show that maximal quantum discord (entanglement) can be obtained in the strong coupling regime. Analytical result corresponding to an effective Hamiltonian is given. In a deep strong coupling regime, sudden death and sudden birth of entanglement are observed, while the peak value of quantum discord is reached periodically. The results of our investigation also suggest that some special quantum state with non-zero quantum discord may be created.