Entanglement dynamics and decoherence of an atom coupled to a dissipative cavity field

In this paper, we investigate the entanglement dynamics anddecoherence in the interacting system of a strongly driventwo-level atom and a single mode vacuum field in the presence ofdissipation for the cavity field. Starting with an initial productstate with the atom in a general pure state and the field in avacuum state, we show that the final density matrix is supportedon \({\mathbb C}^2\otimes{\mathbb C}^2\) space, and therefore, theconcurrence can be used as a measure of entanglement between theatom and the field. The influences of the cavity decay on thequantum entanglement of the system are also discussed. We alsoexamine the Bell-CHSH violation between the atom and the field andshow that there are entangled states for which the Bell-BCSHinequality is not violated. Using the above system as a quantumchannel, we also investigate the quantum teleportation of ageneric qubit state and also a two-qubit entangled state, and showthat in both cases the atom-field entangled state can be useful toteleport an unknown state with fidelity better than any classicalchannel.