M. G. Gladush

Emission spectra and intrinsic optical bistability in a two-level medium

Abstract Scattering of resonant radiation in a dense two-level medium is studied theoretically accounting for local field effects and renormalisation of the resonance frequency. Intrinsic optical bistability is viewed as switching between different spectral patterns of fluorescent light controlled by the incident field strength. Response spectra are calculated analytically for the entire hysteresis loop of atomic excitation. The equations to describe the non-linear interaction of an atomic ensemble with light are derived from the Bogolubov-Born-Green-Kirkwood-Yvon hierarchy for reduced single particle density matrices of atoms and quantised field modes and their correlation operators. The spectral power of scattered light with separated coherent and incoherent constituents is obtained straightforwardly within the hierarchy. The formula obtained for emission spectra can be used to distinguish between possible mechanisms suggested to produce intrinsic bistability in experiments.

Formation of plasmon pulses in the cooperative decay of excitons of quantum dots near a metal surface

The formation of pulses of surface electromagnetic waves at a metal–dielectric boundary is considered in the process of cooperative decay of excitons of quantum dots distributed near a metal surface in a dielectric layer. It is shown that the efficiency of exciton energy transfer to excited plasmons can, in principle, be increased by selecting the dielectric material with specified values of the complex permittivity. It is found that in the mean field approximation, the semiclassical model of formation of plasmon pulses in the system under study is reduced to the pendulum equation with the additional term of nonlinear losses.

Enhancement of fusion rates due to quantum effects in the particles momentum distribution in nonideal plasma media

This study concerns a situation when measurements of the nonresonant cross-section of nuclear reactions appear highly dependent on the environment in which the particles interact. An appealing example discussed in the paper is the interaction of a deuteron beam with a target of deuterated metal Ta. In these experiments, the reaction cross section for d(d, p)t was shown to be orders of magnitude greater than what the conventional model predicts for the low-energy particles. In this paper we take into account the influence of quantum effects due to the Heisenberg uncertainty principle for particles in a non-ideal plasma medium elastically interacting with the medium particles. In order to calculate the nuclear reaction rate in the non-ideal environment we apply both the Monte Carlo technique and approximate analytical calculation of the Feynman diagram using nonrelativistic kinetic Green’s functions in the medium which correspond to the generalized energy and momentum distribution functions of interacting particles. We show a possibility to reduce the 12-fold integral corresponding to this diagram to a fivefold integral. This can significantly speed up the computation and control accuracy. Our calculations show that quantum effects significantly influence reaction rates such as p +7Be, 3He +4He, p +7Li, and 12C +12C. The new reaction rates may be much higher than the classical ones for the interior of the Sun and supernova stars. The possibility to observe the theoretical predictions under laboratory conditions is discussed.

Dissipative Optical Solitons in Dense Media with Optical Pumping

The problem of nonlinear scattering of optical pulses in a dense three-level atomic medium with continuous pumping is considered with allowance for the local field effects. The physical requirements on the parameters of the medium and field are formulated, and the ranges of these parameters for which stationary solitons are effectively formed in the model of a quartz waveguide doped with 87Rb atoms are determined using variational methods. It is found that disregarding the local field in this model results in violation of soliton stability in the predicted parameter range.

Cooperative effects in a quartz medium with quantum dots

Features of the generation of super radiance short pulses in a dielectric medium with quantum dots allowing for the nonlinear dissipative effects of the local field are considered. It is shown that the problem can be reduced to an equation of a nonlinear pendulum with an additional term for the harmonic loss/gain.

Dissipative laser bullets in dielectric media containing quantum dots

The formation of three-dimensional spatiotemporal dissipative solitons (laser bullets) in a dense ensemble of two-level quantum dots imbedded into a dielectric host is analyzed theoretically taking into account complex local field corrections. The possibility of satisfying stability conditions for laser bullets in a wide range of concentration and quantum dot size parameters is demonstrated. Substantial increase in dimensions of the found areas of stability when choosing all-dielectric metamaterials as a host medium is revealed.

Formation of sub-picosecond plasmon–polariton pulses via cooperative effects in a waveguide spaser

The formation of surface plasmon–polariton pulses excited in a waveguide spaser during the collective decay of quantum dot excitons distributed in a dielectric layer near a metallic surface is considered. The waveguide spaser’s physical parameters and regimes of generation suitable for the formation of sub-picosecond plasmon–polariton pulses are determined with allowance for dissipative effects in the considered system.

Formation of nonclassical states of vortex solitons in optical fibers with quantum dots

The problem of control for the quantum statistics of dissipative vortex optical solitons when using the Raman scheme of spin-flip transitions in an optical fiber doped with narrow-bandgap semiconductor quantum dots is considered. The possibility of forming individual bounded nonclassical quadrature squeezed light regions appearing within the spatial profile of a formed vortex soliton is demonstrated.

The optical control of spatial dissipative solitons in optical fibers filled with a cold atomic gas

We consider the problem of formation and propagation of optical vortex solitons in hollow-core optical fibres filled with a cold atomic gas for the case of the Raman regime in the Λ-scheme of interaction subject to the Lorentz local field effects and in the presence of optical and atomic perturbations. We shows that the coherent optical control by pump beam in such an atomic medium leads to effective development of dynamical equilibrium of diffraction, nonlinear and dissipative processes necessary to stabilize dissipative vortex solitons. We demonstrate that the generation of acoustic waves even with small amplitudes in the fiber can quickly destroy the soliton mode.