Sudden death and birth of two-atom entanglement with two thermal fields in coupled cavities

Abstract

We investigate the entanglement dynamics of two initially maximally entangled identical atoms, each of which interacts with a single-mode thermal field in the coupled-cavity system. The analytical solution of the concurrence for the two atoms is given when the cavity fields are in the vacuum state. When the cavity fields are initially in thermal states, it is difficult to calculate the dynamics using the exact Hamiltonian, thus an effective Hamiltonian is used for the case of large detuning. For the case of small detuning, we numerically solve the problem and find that sudden death and rebirth emerge while the lost entanglement will never recover when the the mean photon number exceeds a critical value for certain parameters. In addition, for asymmetric mean photon numbers, the time-distribution of the peaks of the concurrence will be almost fixed once the temperature of any cavity keeps constant and the amplitudes of the peak are dominated by the other’s temperature.