NON LINEAR EFFECTS OF SINGLE ATOM IN TWO-PHOTON PROCESSION

Non-linear effects of a single atom in two-photon processes inside a high-Q cavity are examined. The interaction of a single two-level atom with two different modes of quantized field is represented by a nondegenerate two-photon Jaynes-Cummings Model (NTPJCM). By developing a time evolution operator U(t, O), Effective Dipole Squeezing (EDS) is investigated. EDS, under different physical conditions and various initial fields and their intensities, is discussed with the help of two-dimensional graphs.\ud \ud Fluorescence studies in transient regime require that spectra in two-photon processes be investigated. We emphasize that a nondegenerate version of the two-photon laser could be constructed through "dressed atoms" rather than "bare atoms" as active medium. Dressed atomic states are the energy eigenstates of the atom. We calculate the spectra of the nondegenerate two-photon process in a "dressed-atom approach", first in the microwave and then in the optical region. We use the two-time correlation function of atomic dipole operators for the former case and that of field operators for the latter case.\ud \ud We generalize and highlight two-photon processes in A-type three level atom, focusing on its quantum beat and correlated emission regimes. Certain nonclassical effects of radiation emitted by the atom and the role of correlated and uncorrelated photons are thoroughly discussed with the help of three-dimensional graphs