Entanglement and nonlocality versus spontaneous emission in two-atom systems

We study evolution of entanglement of two two-level atoms in the presence of dissipation caused by spontaneous emission. We find explicit formulas for the amount of entanglement as a function of time, in the case of destruction of the initial entanglement and possible creation of a transient entanglement between atoms. We also discuss how spontaneous emission influences nonlocality of states expressed by violation of Bell-CHSH inequality. It is shown that evolving system very quickly becomes local, even if entanglement is still present or produced. (C) 2003 Elsevier B.V. All rights reserved.