Atomic radiative transition probabilities in a continuous medium

B. A. Veklenko

Émile Biémont

S. P. Goreslavskiǐ, Nikolai B. Delone, В. П. Крайнов

Huabing Cai, Li‐Gang Wang

We investigate the effect of the presence of a dielectric medium on the stimulated transition processes of a uniformly moving atom in a thermal radiation field. The cases of atomic subluminal and superluminal motions are considered. The calculated results indicate that the atomic stimulated transition rates depend crucially on the atomic velocity, the temperature of the thermal radiation, the refractive index of medium, and the atomic polarizability. The transition rates are expanded by series in some limiting cases, such as the extreme temperature of thermal radiation, the extreme motion of the atom, and the extremely large refractive index. Our analytical and numerical analyses show that the presence of the dielectric medium has profoundly changed the behaviors and characteristics of the atomic stimulated transition rates, especially when the atom moves faster than the speed of light in the medium. Moreover, the behavior of the transition rates for an atom polarized parallel to the direction of atomic motion is quite distinct from that of an atom polarized perpendicularly to the direction of atomic motion.

Eugeny Korsunsky, Dmitry V. Kosachiov

We propose a scheme for the generation of continuous-wave terahertz (THz) radiation. The scheme requires a medium in which three discrete states in a Λ configuration can be selected, with the THz frequency transition being between the two lower metastable states. The propagation of three-frequency continuous-wave electromagnetic (EM) radiation through a Λ medium is considered. Under resonant excitation, the medium absorption can be strongly reduced owing to quantum interference of transitions, whereas the nonlinear susceptibility is enhanced. This leads to efficient energy transfer among the EM waves, providing the possibility of THz generation. We demonstrate that the photon conversion efficiency is approaching unity in this technique.

Boris Michailovich Smirnov