Quantum transitions in a two-level system in a field of intense monochromatic influx

A. O. Melikyan

Shaoul Ezekiel

Petr A. Braun, George P. Miroshnichenko

Andrey Vladimirovich Soldatov

We studied time-dependent features of high-frequency fluorescent radiation from a two-level quantum system with broken inversion spatial symmetry. The system in question was modelled after a one-electron two-level asymmetric polar semiconductor quantum dot whose electric dipole moment operator has permanent unequal diagonal matrix elements. The dot was permanently excited by incoherent pumping of some sort. Our attention was focused on the evolution of the fluorescence spectrum following abrupt switching on of an additional driving monochromatic field, which frequency is much lower than the optical transition frequency of the quantum dot. An analytical expression for the fluorescence spectrum as a function of the amplitude, initial phase and frequency of the monochromatic driving field, as well as of the pumping intensity and the elapsed time, was derived.

Rodney J. Gush, Herbert P. Gush

A general expression is found for the Green's function of a two-level system interacting with a classical monochromatic field of arbitrary frequency and intensity. The Green's function is first used to calculate the transition probability from the lower to the upper state as a function of the frequency and intensity of the field and a comparison of the results is made with experiment. It is then used to study the problem of scattering. It is found that the spectrum of the scattered radiation consists of a line at the frequency of the field (Rayleigh line) and two satellites symmetrically displaced from the Rayleigh line by an amount depending both on the intensity and frequency of the field. In addition there are emissions at three, five, etc., times the frequency of the field, and accompanying satellites. The cross sections for the production of the Rayleigh line and its satellites, and for the third-harmonic line and its satellites have been calculated for a range of values of the frequency and intensity of the incident field.

Andrey Vladimirovich Soldatov

Abstract We studied spectral properties of high-frequency fluorescent radiation from a two-level quantum system with broken inversion spatial symmetry, which can be implemented as a model of a one-electron two-level asymmetric polar semiconductor quantum dot whose electric dipole moment operator has permanent unequal diagonal matrix elements. The case of the excitation of this system by incoherent pumping of some sort supplemented with an additional driving monochromatic field, which frequency is much lower than the optical transition frequency of the quantum dot, was considered. An analytical expression for the fluorescence spectrum as a function of the amplitude and frequency of the monochromatic driving field, as well as of the pumping intensity, was derived. We also discussed feasible practical applications of the effects under study in the field of quantum optics and optoelectronics for the generation of high-frequency radiation, possessing stationary equidistant spectrum, and for the control of the radiative properties of such nanodevices as spasers (dipole nanolasers).