Entanglement evolution of two remote and non-identical Jaynes-Cummings   atoms
  A detailed treatment of the entanglement dynamics of two distant but non-identical systems is presented. We study the entanglement evolution of two remote atoms interacting independently with a cavity field, as in the double Jaynes-Cummings (JC) model. The four-qubit pairwise concurrences are studied, allowing for asymmetric atom-cavity couplings and off-resonant ineractions. Counter to intuition, imperfect matching can prove advantageous to entanglement creation and evolution. For two types of initial entanglement, corresponding to spin correlated and anti-correlated Bell states \Phi and \Psi, a full, periodic and directed transfer of entanglement into a specific qubit pair is possible, for resonant interactions, depending on the choice of relative couplings. Furthermore, entanglement transfer and sudden death (ESD) can be prevented using off-resonant interactions, although for some initial states, detunings will trigger an otherwise frozen entanglement, to allow a full entanglement transfer. We confirm a conservation rule governing the pairwise entanglement between the non-interacting systems, that for the initial state \Psi the sum of the square of these concurrences (SSC) is conserved. For \Phi, the total SSC is reduced periodically, even to zero in some cases, to reveal a complete and abrupt loss of all non-local pairwise entanglement. 
S. Chan, M.D. Reid, and Z. Ficek