The properties of the two-dimensional (2D) magnetoexcitons in the GaAs-type quantum wells subjected to the action of a strong perpendicular magnetic field and of the 2D Wannier-Mott excitons in the transition metal dichalcogenides with the binding energy determined by the direct Coulomb electron-hole (e-h) interaction and with the summary e-h spin projections F = ± 1 are compared. In both cases the exchange e-h Coulomb interaction leads to the creation of the symmetric and asymmetric superposition states formed by two bare exciton states with F = ± 1. The superposition states are characterized in different variants by the Dirac cone dispersion laws and with quantum interference effects in the optical quantum transitions from the ground state of the crystal.
The energy spectrum of the two-dimensional cavity magnetoexciton-polaritons has been investigated previously, using exact solutions for the Landau quantization (LQ) of conduction electrons and heavy holes (hhs) provided by the Rashba method. Two lowest LQ levels for electrons and three lowest Landau levels for hhs lead to the construction of the six lowest magnetoexciton sates. They consist of two dipole-active, two quadrupole-active, and the two forbidden quantum transitions from the ground state of the crystal to the magnetoexciton states. The interaction of the four optical-active magnetoexciton states with the cavity-mode photons with a given circular polarization and with well-defined incidence direction leads to the creation of five magnetoexciton-polariton branches. The fifth-order dispersion equation is examined by using numerical calculations and the second-order dispersion equation is solved analytically, taking into account only one dipole-active magnetoexciton state in the point of the in-plane wave vector k→∥=0. The effective polariton mass on the lower polariton branch, the Rabi frequency, and the corresponding Hopfield coefficients are determined in dependence on the magnetic-field strength, the Rashba spin–orbit coupling parameters, and the electron and hole g-factors.
The Hamiltonian describing the interaction of the two-dimensional (2-D) magnetoexcitons with photons propagating with arbitrary-oriented wave vectors in the three-dimensional (3-D) space is deduced. The magnetoexcitons are characterized by the numbers ne and nh of the electron and hole Landau quantizations, by circular polarization σ⃗M of the holes in the p-type valence bands and by in-plane wave vectors k⃗‖. The photons are characterized by the wave vectors k⃗ with in-plane component k⃗‖ and perpendicular component kz, which is quantized in the case of microresonator. The interaction is governed by the conservation law of the in-plane components k⃗‖ of the magnetoexcitons and photons and by the rotational symmetry around the axis perpendicular to the layer, which leads to the alignment of the magnetoexcitons under the influence of the photons with circular polarization σ⃗±k⃗ and with probability proportional to |(σ⃗±k⃗⋅σ⃗∗M)|2.
It's hard to imagine a modern city view without some drawings and inscriptions, usually called "graffiti". Traditional
cleaning methods do not suit modern requirements. Investigation of possibilities of laser assisted paints removing is
described in this article. The conditions for removing different paints from different surfaces were defined.
The temperature dependencies of luminescence spectra of the InAs/GaAs quantum dots L0 (EL0 = 1.235 eV), L1 (EL1 = 1.290 eV) and I1 (EI1 = 1.343 eV) and wettings layer (WL) (EWL = 1.408 eV) have been investigated at P = 0 and P = 15 kbar. The InAs quantum dots on vicinal substrates GaAs at misorientation angle 7° [001] have been grown in submonolayer migration enhanced epitaxy mode (SMEE). The activation energies have been determined from the temperature quenching of luminescence. Their dependence on a value of hydrostatic pressure have been studied. The available scheme of energy levels of quantum dots has been proposed.
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