Influence of atomic coherence on entanglement between dipole-coupled Jaynes-Cummings and isolated atom

We investigated the entanglement of a quantum system consisting of a Jaynes-Cummings atom, thermal lossless cavity and an isolated atom. The analytical expressions of the atom-atom negativity for separable, separable coherent and entangled initial atomic states were obtained. The influence of initial atomic coherence, detuning between the atomic transition frequency and the field frequency and direct dipole-dipole interaction on an atom- atom entanglement is examined. We showed that for a separable and separable coherent initial atomic states a detuning might cause high atom-atom entanglement in the presence of the dipole-dipole interaction even for thermal field with high intensity. We also obtained that for entangled initial atomic states a detuning causes a stabilization of an entanglement oscillations.