Quantum Discord of Two Atoms Interacting with a Single-mode Thermal Field

This paper investigates the quantum discord and entanglement of two atoms when they simultaneously interact with a single-mode thermal field. The results show that, the two atoms which are initially in separate states can be entangled by a thermal field. However, with increase of the mean photon number, the value of the entanglement decreases and disappears when the temperature of the cavity is high enough (corresponding to the large value of the mean photon number). In stark contrast, the quantum discord does not decrease, but gradually reaches stable value at high temperature. In addition, when the two atoms are initially the Werner mixed state, we have found that, a large amount of quantum discord is exist even in the region where the entanglement is zero, which is a strong signature for the presence of non classical correlations. These results indicate that, the quantum discord is more resistant to the environment's disturbance than the entanglement for higher temperatures.