Effect of preparation procedures on the system’s entanglement evolution
Department of Physics, Shandong University, Jinan 250100, P.R. China
Received: 10 March 2012
Received in final form: 17 June 2012
Published online: 12 September 2012
For an open quantum system, different preparation procedures result in the same evolution when the system and the environment are separate. However, there always exist initial correlations between the system and the environment. In this paper, we investigate how the different preparation procedures affect the entanglement evolution when there exist initial correlations. We here consider two important preparation procedures, the stochastic preparation procedure and the projective preparation procedure. We calculate the entanglements corresponding to each of the two procedures and examine the difference between them. Our result shows that the projective preparation procedure is more detrimental to entanglement evolution than the stochastic preparation procedure for this model. The entanglement difference arising from the two procedures is generally significant. Yet, we also find that the relative difference can be washed out in the case of weak interaction or low temperature, and it becomes smaller and smaller in an oscillating way as the time goes to infinity. We arrive at these points in two cases of environments, the independent environment and the common environment, both of which come to the same conclusion.
Key words: Quantum Information
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2012