Drift velocity of edge magnetoplasmons due to magnetic edge channels

Edge magnetoplasmons arise on a boundary of conducting layer in perpendicular magnetic field due to an interplay of electron cyclotron motion and Coulomb repulsion. Lateral electric field, which confines electrons inside the sample, drives their spiraling motion in magnetic field along the edge with the average drift velocity contributing to the total magnetoplasmon velocity. We revisit this classical picture by developing fully quantum theory of drift velocity starting from analysis of magnetic edge channels and their electrodynamic response. We derive the quantum-mechanical expression for the drift velocity, which arises in our theory as a characteristic of such response. Using the Wiener-Hopf method to solve analytically the edge mode electrodynamic problem, we demonstrate that the edge channel response effectively enhances the bulk Hall response of the conducting layer and thus increases the edge magnetoplasmon velocity. In the quasiclassical long-wavelength limit of our model, the drift velocity is simply added to the total magnetoplasmon velocity, in agreement with the classical picture.Comment: 10 pages, 6 figure

Superconductor-polariton non-dissipative drag in optical microcavity

We consider non-dissipative drag between Bose-condensed exciton polaritons in optical microcavity and embedded superconductors. This effect consists in induction of a non-dissipative electric current in the superconductor by motion of polariton Bose condensate due to electron-polariton interaction, or vice versa. Using many-body theory, we calculate the drag density, characterizing magnitude of this effect, with taking into account dynamical screening of the interaction. Hoping to diminish the interaction screening and microcavity photon absorption, we consider atomically-thin superconductors (both conventional s-wave and copper-oxide d-wave) of planar and nanoribbon shapes. Our estimates show that in realistic conditions the drag effect could be rather weak but observable in accurate experiments in the case of dipolar interlayer excitons in transition metal dichalcogenide bilayers. Use of spatially direct excitons, semiconductor quantum wells as the host for excitons, or thin films of bulk metallic superconductors considerably lowers the drag density.Comment: 10 pages, 6 figure

Coupled system of electrons and exciton-polaritons: Screening, dynamical effects, and superconductivity

Bose-Fermi systems such as mixtures of electrons with excitons or exciton-polaritons are extensively discussed as candidates to host a variety of intriguing phenomena, including polaron formation, drag effects, supersolidity, and superconductivity. In this work, assuming the strong-coupling regime between the semiconductor excitons and cavity photons, we develop the many-body theory approach addressing the interplay of different types of interaction among various species in such a mixture, wherein we take into account dynamical density responses of both the Bose-condensed exciton-polaritons and the two-dimensional electron gas inside an optical microcavity. As was anticipated previously, at high enough polariton densities the lower hybrid mode of the system's excitation spectrum acquires a roton minimum, making the system prone to superconducting pairing in the vicinity of the roton instability. We analyze the possibility of polariton-BEC-mediated superconductivity in the electron gas taking into account full momentum and frequency dependence of the gap, as well as in the Eliashberg approach where the momentum dependence is neglected, and in the Bardeen-Cooper-Schrieffer approach that discards the frequency dependence and dynamical effects. Considering the interaction screening in Thomas-Fermi and in random-phase approximations, we estimate the critical temperatures of superconductivity to be not larger than 0.1 K in the vicinity of instability. As possible realizations of the coupled polariton-electron system, semiconductor quantum wells and two-dimensional transition metal dichalcogenides are considered.Comment: 19 pages, 8 figure