Degree of entanglement for two fields interacting with a two-level system

In the present communication, we consider a model of the Hamiltonian which represents the interaction between two-field and two-level atom, where the multiphoton processes is involved. We study the influences of Stark shifts on the degree of entanglement for the system via nondegenerate Raman two-photon transition. The effect of Stark shift on the entropy and the entanglement is analyzed. It is shown that this effect changes the quasiperiod of the field entropy, as well as the entanglement between the particle and the field.