Dynamics of an M-level equidistant radiator in the presence of a thermal electromagnetic field

Abstract

We study the spontaneous emission of a multilevel equidistant excited quantum oscillator (nuclei, atoms, molecules) in the case in which the symmetry of the dynamical transitions between the levels is submitted to the SU(1,1) symmetry group and compare our results with those well known for the SU(2) symmetry. It is shown that the equidistant radiator in the process of spontaneous decay in the case of SU(1,1) symmetry exhibits either only acceleration or only a decrease in spontaneous emission rates, while in the case of SU(2) symmetry the radiation pulse is similar to that for the Dicke super-radiance. The exact steady-state solution for the atomic density operator for an equidistant radiator driven by a totally incoherent broad-band (chaotic) field for a SU(1,1) symmetry group is obtained using the Fokker-Planck equation. It is found that for a strong-field limit in the case of SU(1,1) symmetry the fluctuations in the atomic population increase with increasing intensity of the external field and do not achieve their maximal value as in the case of SU(2) symmetry. Moreover, in the case of SU(1,1) transition symmetry we find that there is a superbunching effect for certain values of group parameter I, while in the case of SU(2) symmetry only bunching and antibunching occur. It is found that for vanishing values of the external field intensity the second-order intensity correlation function achieves negative values.