Eur. Phys. J. D 41, 377-383 (2007)
https://doi.org/10.1140/epjd/e2006-00216-x

Robust and fragile Werner states in the collective dephasing

¹ Chinese Center of Advanced Science and Technology (World Laboratory), P.O. Box 8730, Beijing, P.R. China
² Zhejiang Institute of Modern Physics and Department of Physics, Zhejiang University, Hangzhou, 310027, P.R. China

Corresponding author: ^a Stephenli74@yahoo.com.cn

Received: 8 June 2005
Revised: 30 August 2006
Published online: 22 September 2006

Abstract

We investigate the concurrence and Bell violation of the standard Werner state or Werner-like states in the presence of collective dephasing. It is shown that the standard Werner state and certain kinds of Werner-like states are robust against the collective dephasing, and some kinds of Werner-like states is fragile and becomes completely disentangled in a finite-time. The threshold time of complete disentanglement of the fragile Werner-like states is given. The influence of external driving field on the finite-time disentanglement of the standard Werner state or Werner-like states is discussed. Furthermore, we present a simple method to control the stationary state entanglement and Bell violation of two qubits. Finally, we show that the theoretical calculations of fidelity based on the initial Werner state assumption well agree with previous experimental results.