Influence of a Kerr-like medium on the evolution of field entropy and entanglement in a three-level atom

We have investigated the evolution of the field quantum entropy and the ent anglement of the atom field in a three-level atom, with an additional Kerr- like medium for one mode. The exact results are employed to perform a caref ul investigation of the temporal evolution of the entropy. A factorization of the initial density operator is assumed, where the privileged field mode is in a coherent state. We invoke the mathematical notion of maximum varia tion of a function to construct a measure for entropy fluctuations. The eff ect of a Kerr-like medium on the entropy is analysed. It is shown that the addition of the Kerr medium has an important effect on the properties of th e entropy and the entanglement. The results show that the effect of the Ker r medium changes the quasiperiod of the held entropy evolution and entangle ment between the atom and the held. The general conclusions reached are ill ustrated by numerical results.