'Dressed' atom radiation processes which are first order in the weak field

[摘要] Nonlinear processes of light scattering on a two-level system near resonance are considered. The problem is reduced to the emission and absorption of a coupled system, formed by a strong resonant field and a two-level system, having a non-factorizing wave function. Various regimes of emission and absorption of the coupled system are determined by the parameter alpha = /2dE/(h) over bar Delta/, where E is the amplitude of the strong resonant field, d is the electric dipole moment of the transition 1-2 of the unperturbed atom, Delta is the detuning off resonance, Delta = E-2 - E-1 - (h) over bar omega, with E-1,E-2 being the energies of, respectively, lower and upper atomic levels, and io the carrier frequency of the resonant field. Two limiting cases of switching on the interaction between the atom and field are considered, those of the adiabatic and the sudden switching on; these two cases allow simple analytical solutions and lead to essentially differing physical results, either for the probabilities of the processes of the first order with respect to the weak field, or for their coherent properties. Note that at alpha much less than 1 the conventional perturbation technique is applicable. This means that for weak fields we can use perturbation method because the corresponding alpha' much less than 1. The nonlinear resonance fluorescence and the amplification of weak radiation field by the coupled system at optical frequencies are considered. The coherent properties of the emission of the coupled system are studied which is important for the problems of propagation in gaseous media, coherence and quantum computation. (C) 1998 Elsevier Science B.V. All rights reserved.

[发布日期] 1998-12-15

[关键词] nonlinear optics;fluorescence;light amplification;coherence;quasiclassical theory;quantum computation