The Physical Transient Spectrum and Squeezing of a Three-Level Atom Interacting with Two-Mode Field in Finite Pair Coherent State in the Presence of a Classical External Field

We investigate effects of a classical external field and the initial state of the field on the nonlinear interaction of a Λ-type three-level atom with the two-mode field through the Raman type interaction. Appropriate canonical transforms are performed for atomic states. The analytic solution to the model is obtained, using the Schrödinger differential equation. The wave function is obtained under specific initial conditions of the atom and field. The effect of a classical external field and the initial state of the field on the population occupations, the squeezing phenomenon, and the atomic emission spectrum are studied. The collapse–revival phenomena are affected by the presence of the classical field. Increasing the activation of the role of the initial state of the field improves the phenomena of collapses and revivals. The squeezing intervals decrease with increase in the classical field effect. The squeezing intervals increase with decrease of the parameter of the initial state of the field. The maximum values of the emission spectrum are improved after taking into account the classical field. In addition, the peaks significantly decrease after reducing the influence of both the bandwidth of the filter and the interaction time.