arXiv subjects

Sergueï V. Andreev

Publications and source records attributed to Sergueï V. Andreev.

5 recordsLinked to original sources

arXiv2026

Heisenberg-Langevin theory of an exciton mirror

We develop a Heisenberg-Langevin theory of an exciton mirror accounting for the retardation and the long-range electron-hole exchange. A particular case of a strong transverse magnetic field is analyzed in detail. The optical bistability due to repulsion between the excitons inside the light cone appears to be prone to a modulational instability towards the non-radiative surface polariton modes. Above the corresponding threshold, the pumped 2D exciton gas acts as an optical parametric generator of twin polariton beams. Conversely, below the threshold, the mirror acquires the phase-conjugating properties.

cond-mat.mes-hall↗

arXiv2023

Controllable fusion of electromagnetic bosons in two-dimensional semiconductors

We propose a physical principle for implementation of controllable interactions of identical electromagnetic bosons (excitons or polaritons) in two-dimensional (2D) semiconductors. The key ingredients are tightly bound biexcitons and in-plane anisotropy of the host structure due to, e.g., a uniaxial strain. We show that anisotropy-induced splitting of the radiative exciton doublet couples the biexciton state to continua of boson scattering states. As a result, two-body elastic scattering of bosons may be resonantly amplified when energetically tuned close to the biexciton by applying a transverse magnetic field or tuning the coupling with the microcavity photon mode. At the resonance, bosonic fields undergo quantum reaction of fusion accompanied by their squeezing. For excitons, we predict giant molecules (Feshbach dimers) which can be obtained from a biexciton via rapid adiabatic sweeping of the magnetic field across the resonance. The molecules possess non-trivial entanglement properties. Our proposal holds promise for the strongly-correlated photonics and quantum chemistry of light.

cond-mat.quant-gas↗

arXiv2023

Coupled oscillator model of a trapped Fermi gas at the BEC-BCS crossover

We address theoretically the puzzling discontinuity of the radial quadrupole mode frequency observed in a trapped Fermi gas across the BEC-BCS crossover. We apply the scaling transformation to a two-channel model of a resonant Fermi superfluid and argue that the frequency downshift in the crossover region is due to Feshbach coupling of the molecular Bose-Einstein condensate (BEC) to the surrounding Fermi sea. The Bose and Fermi components of the gas act as coupled macroscopic oscillators. The frequency jump corresponds to the point where the closed-channel molecules are entirely converted into the Fermi sea. This implies linear scaling of the "critical" detuning between the scattering channels with the Fermi energy, which can be readily verified in an experiment.

cond-mat.quant-gas↗

arXiv2021

Pairing of electro-magnetic bosons under spin-orbit coupling

We discuss pairing of light-matter bosons under effective spin-orbit (SO) coupling in two-dimensional semiconductors. The SO coupling is shown to induce dynamical broadening of a two-body bound state. Application of a transverse magnetic field yields the rich Feshbach resonance phenomenology. We predict quantum bosonic halos with a synthetic angular momentum L=2. The d-wave-like dressing of the nominally s-wave bound state is induced by SO coupling to the continuum in the open channel. The fundamental properties of the emergent quantum number remain to be explored.

cond-mat.quant-gas↗

arXiv2020

Dipolar polaritons squeezed at unitarity

Interaction of dipolar polaritons can be efficiently tuned by means of a shape resonance in their excitonic component. Provided the resonance width is large, a squeezed population of strongly interacting polaritons may persist on the repulsive side of the resonance. We derive an analytical expression for the polariton coupling constant and show that it may have very large values in typical experimental conditions. Our arguments provide a new direction for the quest of interactions in quantum photonics.

cond-mat.quant-gas↗