Nonequilibrium polariton condensation in biannular optically induced traps

We report the mean field model of nonequilibrium polariton condensation in annular effective non-Hermitian potential traps, stemming from incoherent optically induced excitonic reservoirs of annular shape. We solve the linearized extended Gross-Pitaevskii equation in the approximation of two delta-function effective shell potentials for complex spectra of trapped polariton modes and calculate corresponding condensation threshold optical pumping powers. The exhaustive map of condensate quantum number transitions in the multi-dimensional space of trap parameters, including a cascade of topological charge increments, is drastically different from the single annular trap case in topology and the range of accessible condensate states.Comment: 9 pages, 6 figure

Non-adiabatic polariton condensation in annular optical traps

We explore formation and dynamics of nonequilibrium bosonic exciton-polariton condensates in annular optically induced traps. For the vicinity of condensation pumping threshold, we develop the two-mode model, accounting for counter-rotating quantized vortices and corresponding angular harmonics in the incoherent excitonic reservoir density. Identifying the range of parameter, in which adiabatic elimination of the reservoir is valid, we extend the analytic model beyond the adiabatic approximation. In the circularly symmetric case, we predict a neutral equilibrium phase due to spontaneous breaking of the continuous symmetry, condensate multistability and limit cycle dynamics. We also account for weak trap asymmetry to show that non-adiabaticity of the coupled condensate-reservoir system prevents formation of giant vortices and outline experimental conditions for their observation.Comment: 12 pages, 7 figure

Pseudoconservative dynamics of coupled polariton condensates

© 2021 The Authors. Published by American Physical Society. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1103/PhysRevResearch.3.033187Open-dissipative systems obeying parity-time (PT) symmetry are capable of demonstrating oscillatory dynamics akin to the conservative systems. In contrast to limit cycle solutions characteristic of nonlinear systems, the PT-symmetric oscillations form a continuum of nonisolated orbits. However, precise sculpturing of the real potential and the gain-loss spatial profiles required for establishing of the PT symmetry is practically challenging. The optical devices, such as lasers, exhibit relaxation dynamics and do not operate as the PT-symmetric systems. Here we demonstrate how these constraints can be overcome. We predict that a pair of optically trapped polariton condensates (a polariton dimer) can be excited and operated in the oscillating regime typical of the isolated systems. This regime can be realized in the presence of both dissipative and conservative coupling between the condensates and can be maintained at an arbitrary external pump intensity. Every orbit is characterized by a frequency comb appearing in the spectrum of a dimer in the presence of the conservative nonlinearity. Our results pave the way for the creation of the optical computing devices operating under the constant-wave external pumping.Published versio

Ratchet effects in two-dimensional systems with a lateral periodic potential

Radiation-induced ratchet electric currents have been studied theoretically in graphene with a periodic noncentrosymmetric lateral potential. The ratchet current generated under normal incidence is shown to consist of two contributions, one of them being polarization-independent and proportional to the energy relaxation time, and another controlled solely by elastic scattering processes and sensitive to both the linear and circular polarization of radiation. Two realistic mechanisms of electron scattering in graphene are considered. For short-range defects, the ratchet current is helicity-dependent but independent of the direction of linear polarization. For the Coulomb impurity scattering, the ratchet current is forbidden for the radiation linearly polarized in the plane perpendicular to the lateral-potential modulation direction. For comparison, the ratchet currents in a quantum well with a lateral superlattice are calculated at low temperatures with allowance for the dependence of the momentum relaxation time on the electron energy.Comment: 8 pages, 4 figure