Entanglement Transfer From Two-mode Light Fields To Mixed Atoms Under Intensity-dependent Coupling

Entanglement is one of the most striking features of quantum mechanics and the key resource of quantum information. Two nonclassical light fields called pair-coherent state and SU(1,1) coherent state has the predominant property in the entanglement of two modes, so theoretically speaking, it can act as information carrier in quantum teleportation. If two atoms which are spatially separated interact with these two-mode light fields, then entanglement can be transferred from the field to the atoms. But in a real process of teleportation, there is interaction between whole system and environment, so the information on the carrier are destroyed. The phenomenon of decoherence will happen, which is detrimental to quantum computation and quantum teleportation. Therefore, it is necessary to investigate the atoms which are prepared in mixed states when field interacts with fields. In this article we study the entanglement transfer from SU(1,1) coherent state and pair-coherent state to mixed atoms by using Jaynes-Cummings model with different forms of intensity-dependent coupling. Then we can obtain the atomic entanglement from the negativity criterion and consider the effects of the parameters of light fields. It's found that suitable form of intensity-dependent coupling can enhance the entanglement transfer and makes it evolve periodically. Even for the mixed initial atomic states, the maximum value of entanglement and the periodical evolvement are kept. It's also shown that the photon number difference q between the two modes plays a key role. When q is odd, the maximum entanglement between the atoms is less than that when q is even.