Quantum Discord and Entanglement between Two Two-Level Atoms in a two-photon Jaynes-Cummings model with an added kerr Medium

Entanglement and Discord are highly complex phenomenon, and of great importance in quantum theory because of its various applications in quantum information processing. Because of this, here, we study and analyze both of them according to two coupled two-level atoms with a single-mode quantized electromagnetic field in a cavity via the degenerate two-photon transition. We consider the entire system of atom-field in a thermal equilibrium with an environment and analysis the effect of the temperature on these correlations. The effect of atom-atom and Kerr–type couplings in quantum discord and entanglement between the atoms is studied as well. As a result, it has been shown that the quantum discord decreases asymptotically to zero when the temperature increases. The results also indicate that the entanglement suddenly disappears during the evaluation, however the quantum discord remains non-zero. Then the quantum discord is considered as an indicator of disentanglement.