arXiv subjects

V. M. Kovalev

Publications and source records attributed to V. M. Kovalev.

62 records · Page 4Linked to original sources

arXiv2018

Radiation Pressure Quantization

Kepler's observation of comets tails initiated the research on the radiation pressure of celestial objects and 250 years later they found new incarnation after the Maxwell's equations were formulated to describe a plethora of light-matter coupling phenomena. Further, quantum mechanics gave birth to the photon drag effect. Here, we predict a novel universal phenomenon which can be referred to as quantization of the radiation pressure. We develop a microscopic theory of this effect which can be applied to a general system containing Bose-Einstein-condensed particles, which possess an internal structure of quantum states. By analyzing the response of the system to an external electromagnetic field we find that such drag results in a flux of particles constituting both the condensate and the excited states. We show that in the presence of the condensed phase, the response of the system becomes quantized which manifests itself in a step-like behavior of the particle flux as a function of electromagnetic field frequency with the elementary quantum determined by the internal energy structure of the particles.

cond-mat.mes-hall↗

arXiv2017

Paramagnetic resonance in spin-polarized disordered Bose-Einstein condensates

We study the pseudo-spin density response of a disordered two-dimensional spin-polarized Bose gas of exciton polaritons to weak alternating magnetic field, assuming that one of the spin states of the doublet is macroscopically occupied and Bose-condensed while the occupation of the other state remains much smaller. We calculate spatial and temporal dispersions of spin susceptibility of the gas taking into account spin-flip processes due to the transverse-longitudinal splitting. Further, we use the Bogoliubov theory of weakly-interacting gases and show that the time-dependent magnetic field power absorption exhibits double resonance structure corresponding to two particle spin states (contrast to paramagnetic resonance in regular spin-polarized electron gas). We analyze the widths of these resonances caused by scattering on the disorder and show that, in contrast with the ballistic regime, in the presence of impurities, the polariton scattering on them is twofold: scattering on the impurity potential directly and scattering on the spatially fluctuating condensate density caused by the disorder. As a result, the width of the resonance associated with the Bose-condensed spin state can be surprizingly narrow in comparison with the width of the resonance associated with the non-condensed state.

cond-mat.mes-hall↗

arXiv2016

Ultrafast exciton-polariton scattering towards the Dirac points

Using the Feynman-Dyson diagram technique, we study nonlinear polariton-polariton scattering in a two-dimensional micropillar-based optical superlattice with hexagonal symmetry. We demonstrate that both the emerging polariton chirality and the loop Feynman diagrams up to infinite order should be strictly accounted for in the evaluation of the self-energy of the system. Further, we explicitly show that in such a design the time of polariton scattering towards the Dirac points can be drastically decreased which can be used, for instance, in engineering novel classes of polariton lasers with substantially reduced thresholds.

cond-mat.mes-hall↗

arXiv2014

Rayleigh surface wave interaction with 2D exciton Bose-Einstein condensate

We describe the interaction of the Rayleigh surface acoustic wave (SAW) traveling on the semiconductor substrate and interacting with excitonic gas in a double quantum well located on the substrate surface. We study the SAW attenuation and its velocity renormalization due to coupling with excitons. Both the deformation potential and piezoelectric mechanisms of the SAW-exciton interaction are considered. We focus our attention on the frequency and excitonic density dependencies of the SAW absorption coefficient and velocity renormalization at temperatures both above and well below the critical temperature of Bose-Einstein condensation of excitonic gas. We demonstrate that the SAW attenuation and velocity renormalization are strongly different below and above the critical temperature.

cond-mat.quant-gas↗

arXiv2013

Impurity Screening and Surface Acoustic Wave Absorption in a Dipolar Exciton Condensate at Finite Temperatures

We describe the behavior of a repulsively interacting Bose-Einstein condensate of indirect dipolar exciton gas in a double quantum well (QW) system under external static or dynamic electric fields at finite temperatures. Electrostatic perturbation is considered to be created by an impurity atom or shot-range defect of QW fluctuation. The screening of this defect potential by an exciton condensate is studied. We find asymptotic spatial dependence of the screened potential and analyse its dependence on the temperature and exciton concentration. It is shown that the asymptotic of the screened potential has a steep power law dependence in contrast to the well known results of electron gas. This peculiarity reflects the bosonic nature of the exciton condensate. The behavior of exciton condensate under external alternative field created by a surface acoustic wave (SAW) is examined in detail. We focus our attention on the dependence of SAW absorption coefficient on temperature and exciton concentration. We found that at zero temperatures Landau damping does not contribute to the SAW absorption, but the Belyaev mechanism produces unusual behavior of SAW absorption coefficient on exciton concentration: if the exciton concentration exceeds some critical value, the SAW absorption vanishes. At finite temperatures Landau damping comes into action and results in washing out the sharp absorption behavior. Such unusual SAW absorption properties can be used for experimental evidence of the exciton condensation. This method is also applicable to the experimental testing of both dark and bright exciton condensates, that is impossible to do with the optical luminescence technique.

cond-mat.mes-hall↗

arXiv2013

Nonlinear Effects in Multi-Photon Polaritonics

We consider theoretically nonlinear effects in a semiconductor quantum well embedded inside a photonic microcavity. Two-photon absorption by a 2p exciton state is considered and investigated; the matrix element of two-photon absorption is calculated. We compute the emission spectrum of the sample and demonstrate that under coherent pumping the nonlinearity of the two photon absorption process gives rise to bistability.

cond-mat.mes-hall↗

arXiv2013

Rashba plasmon polaritons in semiconductor heterostructures

We propose a concept of surface plasmon-polariton amplification in the structure comprising interface between dielectric, metal and asymmetric quantum well. Due to the Rashba spin-orbit interaction, mimina of dispersion relation for electrons in conduction band are shifted with respect to the maximum of dispersion dependence for holes in $Γ$-point. When energy and momentum intervals between extrema in dispersion relations of electrons and holes match dispersion relation of plasmons, indirect radiative transition can amplify the plasmons; excitation of leaky modes is forbidden due to the selection rules. Efficiency of the indirect radiative transition is calculated and design of the structure is analysed.

cond-mat.mes-hall↗

arXiv2002

Quantum wires and dots driven by intense surface acoustic waves and the quantum attenuation of sound in an electron plasma

We develop a quantum theory of the nonlinear interaction between intense surface acoustic waves and electrons of a quantum well in the regime of moving quantum wires and dots. The quantum nonlinear interaction qualitatively differs from the classical one. In a system of electron wires driven by an acoustic wave the sound attenuation strongly decreases with increasing the sound intensity. However, even in the quantum limit the sound attenuation in the electron system remains nonzero due to residual scattering by impurities in the lowest subband. In the case of electron dots formed by two waves moving in the perpendicular directions, the calculated dissipation vanishes at high sound intensity because of the fully quantized spectrum. Besides, moving quantum dots can be formed by a single acoustic wave propagating along a system of etched quantum wires. We show that the quantum regime of the attenuation can exist in high-mobility GaAs quantum wells where the heating can not destroy the quantum state.

cond-mat.mes-hall↗