Quantum entanglement in the SU(1,1)-related coherent fields interacting with a moving atom

The entanglement properties of the SU(1,1)-related coherent fields interacting with a moving atom via the two-photon transition are investigated. We discuss the quantum entanglement between the SU(1,1)-related coherent fields and the moving atom by using the quantum reduced entropy and that between the SU(1,1)-related coherent fields by using the quantum relative entropy. It is shown that we can obtain the maximal entangled state between the fields and the moving atom and the high degree of entanglement between the SU(1,1)-related coherent fields can be preserved for some choiced system parameters.