Entanglement of an Effective Two-Level Atom Interacting with Two Quantized Field Modes

Abstract

Starting from a three-level atom coupled to two modes of a radiation field, we derive a Raman-coupled Hamiltonian. The exact results are employed to carry out a careful investigation of the temporal evolution of the entropy. A factorization of the initial density operator is assumed, with the privileged field modes being in a coherent state. We invoke the mathematical concept of the maximum variation of a function to construct a measure for entropy fluctuations. It is shown that when the individual modes of the field are far detuned from the intermediate atomic level, there is a dynamical Stark shift induced by the Kerr-like medium. The results show that the Kerr effect creates the superstructure of atomic Rabi oscillation and changes the quasiperiod of the field entropy evolution and entanglement between the atom and the field. The dynamic behavior of the mean atomic level occupation probabilities are investigated numerically as functions of time. A number of novel phenomena are discovered and discussed.