The interaction of a three-level λ-type atom with two-mode,circularly polarized electromagnetic field is studied in this paper. In the dipole-approximation,the population of atomic states at arbitrary time is obtained by means of the exact wave function of Schrdinger equation.
Based on this solution for Schrǒdinger equation, the atom lifetime in an electromagnetic wave of circular polarization is studied. When the frequency of a circularly polarized electromagnetic wave is equal to the atomic frequency, the atom lifetime of tow level atom is not influenced by the electromagnetic wave. For a ∧ type three level atom in a circularly polarized electromagnetic wave, we modulate the frequency of the electromagnetic wave to study the atom lifetime and show that the approximate condition in this paper is rational.
Semi-quantum or full-quantum electromagnetically induced transparency has been fully studied for three-level atoms in a weak field approximation method, where probe field is very wea ker than the coupling field. The weak field approximation is no t valid in full-quantum model where the number of coupling photons is not so large. In the present article, the master equations for the interaction of two-mode photons with a three-level Λ -type atom are exactly solved and the exact dispersion and absorption spectra for the probe beam photons are also obtained analytically. The results of the exact scheme are compared with the corresponding results in the weak field approximation method in full-quantum and semi-classi cal models.