Entanglement Between a Single Two-Level Atom and Quantum Systems of N-Level Atoms in the Presence of an External Classical Field

Abstract

We study a single two-level atom interacting with quantum systems of N-level atoms in the presence of an external classical field. We obtain an analytic solution under a specified condition. Then we determine the time-dependent wave function through the evolution operator and employ the wave function obtained for careful investigation of the temporal evolution of the atomic inversion and linear entropy, where the influence of the external classical field is examined. Our study of the linear entropy shows that the system is almost in a mixed state, and the maximum value of entanglement occurs through the linear entropy. Furthermore, we examine the variance squeezing and entropy squeezing for different values of the external classical field parameter, which leads to different observations of the squeezing in the quadratures. In particular, it leads to an increase in the amount of squeezing for all quadratures, as well as the squeezing period.