Zero-Absorption Isolines in a 2-Photon 2-Level Atom Model

The c-number atomic Bloch equations modelling the coupling of a 2-photon 2-1evel single atom with a non-resonant （A # O） squeezed vacuum （SV） radiation reservoir show that： （i） The quantum interference （QI） process, of parameter f O, between the 2-photon transition channels causes coupling of the atomic variables （inversion and polarisation）, and, （ii） The SV reservoir parameters （N, M） induce periodic coefficients and hence inhibited oscillatory behaviour in the atomic variables. Perturbative analytical solutions of these non-autonomous B1och equations are derived and used to calculate the absorption spectrum of a weak field probing the system. Of particular, the zero-absorption isolines in the relevant （N, f）- and （A, f ）-planes of the the largest set of points, where absorption is zero, in parameter （M） of the SV reservoir. system parameters are identified computationally. It is found that, the （A, f）-plane depends on the choice of the degree of squeezing