Nonlinear Interaction and Entanglement Transfer from SU（1,1） Coherent State to Mixed Atoms

For nonlinear interactions with different forms of intensity-dependent coupling, entanglement transfer from the correlated two-mode SU（1,1） coherent states （SCS） to the initially separable and mixed atoms is investigated. It is found that suitable intensity-dependent coupling can enhance the entanglement transfer and make the atomic entanglement evolve periodically especially for the initially mixed atomic states. For SCS, the entanglement between the two modes is strengthened with the increase of the photon number difference （PND） between the two modes of the fields. When PND is odd, the entanglement between the atoms is less than that when PND is even.