Time evolution of two-atom entanglement and thermal entanglement in a generalized Jaynes-Cummings model
推广的Jaynes-Cummings模型中原子纠缠的时间演化和热纠缠态

In this paper, we investigate two-atom entanglement in time evolution and the thermal entanglement in a generalized Jaynes-Cummings model by means of concurrence. The result shows that the two-atom entangled state appears with periodicity, which decreases with increasing dipole-dipole coupling between the two atoms. In a finite temperature, the concurrence decreases with increasing temperature, and the thermal entanglement vanishes in this Jaynes-Cummings model when the system temperature reaches the critical temperature, which is proportional to the dipole-dipole coupling strength of the two atoms. For typical experimental data, the critical temperature is on the order of 10 -5K. In addition, there exists the quantum phase transition in this Jaynes-Cummings model.