The entanglement character between atoms in the non-degenerate two photons Tavis-Cummings model

The entanglement character including the so-called sudden death effect between atoms in the non-degenerate two photons Tavis-Cummings model is studied by means of concurrence. The results show that the so-called sudden death effect occurs only for some kind of initial states. In other words, the phenomenon is sensitive to the initial conditions. One can expect the resurrection of the original entanglement to occur in a periodic way following each sudden death event. The length of the time interval for the zero entanglement is dependent on not only the degree of entanglement of the initial state but also the initial state. And the influence of dipole-dipole interaction and different atomic initial states on entanglement between atoms are discussed. The sudden death effect can be weakened by the introducing of dipole-dipole interaction.