On polariton condensation and polariton-mediated superconductivity in novel types of planar microcavities

Abstract

The many-body phenomena in photonic structures are of great interest due to the vast area of potential applications. This thesis is devoted to the theoretical investigations of collective phenomena in different types of semiconductor structures, in particular, parabolic quantum wells, hybrid Bose-Fermi structures, and transition metal dichalcogenide monolayers.

It is shown that the experimentally obtained integrated photoluminescence spectra from the parabolic quantum well in a microcavity can be described with the use of the semiclassical Boltzmann equations. However, contrary to expectations, the ladder mechanism of exciton relaxation does not describe the experimental data, as the relaxation processes in the PQW involve transitions from all levels to the ground state.

The theoretical investigation of the light-mediated superconductivity in hybrid Bose-Fermi systems is performed. The critical temperature of the phase transition is shown to increase with the density of the polariton condensate and to decrease with the density of electron gas in the superconducting layer. Also, a possible mechanism of suppression of superconductivity by the external magnetic field is discussed, which differs in the considered case from the conventional Meissner effect, because the magnetic field penetration depth is longer than the thickness of the superconducting layer.

The possibility of polariton condensation in microcavities with embedded monolayers of transition metal dichalcogenides is discussed. It is shown that these structures are highly promising for the room temperature polaritonics. The first observation of the strong coupling regime and exciton-polariton modes in WSe2 was realised by our collaborators from the Würzburg University. These results have been described by the coupled harmonic oscillator approach.

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