Interaction of A Three-Level Atom (Λ, V, Ξ) With A Two-Mode Field Beyond Rotating Wave Approximation: Intermixed Intensity-Dependent Coupling

Recalling that the rotating wave approximation (rwa) is only valid in the weak coupling regimes, our purpose is to study the hamiltonian dynamics of the interaction between various configurations of a three-level atom of λ-, v- or ξ-type distinctly with a twomode radiation quantized field, while the rwa is not considered. generally, this prevents one to achieve an analytical solution. moreover, as we will show, using the perturbation theory analytical solution can be successfully obtained. according to our considerations, the contribution of counter rotating terms (crts) within the ordinary hamiltonian is equivalent to arriving at some intermixed intensitydependent atom-field coupling as functions of the two modes of the field, i.e., f(𝑛𝑎, 𝑛𝑏). at last, via evaluating the time-dependent atom -field state vector, the effects of crts on a few nonclassical properties of the state of the system as atomic population inversion and photon statistics are numerically studied. it is observed that, the presence of crts in the hamiltonian dynamics destroys the clear patterns of collapse-revival phenomena in the time behavior of the evaluated quantities.