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Register a new userLasing in the Rashba-Dresselhaus spin-orbit coupling regime in a dye-filled liquid crystal optical microcavity
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In the presence of Rashba-Dresselhaus coupling, strong spin-orbit interactions in liquid crystal optical cavities result in a distinctive spin-split entangled dispersion. Spin coherence between such modes give rise to an optical persistent-spin-helix. In this letter, we introduce optical gain in such a system, by dispersing a molecular dye in a liquid-crystal microcavity. We demonstrate both lasing in the Rashba-Dresselhaus regime and the emergence of an optical persistent spin helix.
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Photon thermalisation and condensation in dye-filled microcavities is a growing area of scientific interest, at the intersection of photonics, quantum optics and statistical physics. We give here a short introduction to the topic, together with an explanation of some of our more important recent results. A key result across several projects is that we have a model based on a detailed physical description which has been used to accurately describe experimental observations. We present a new open-source package in Python called PyPBEC which implements this model. The aim is to enable the reader to readily simulate and explore the physics of photon condensates themselves, so this article also includes a working example code which can be downloaded from the GitHub repository.
Skyrmions are topological spin textures of interest for fundamental science and applications. Previous theoretical studies have focused on systems with broken bulk inversion symmetry, where skyrmions are stabilized by easy-axis anisotropy. We investigate here systems that break surface inversion symmetry, in addition to possible broken bulk inversion. This leads to two distinct Dzyaloshinskii-Moriya (DM) terms with strengths $D_perp$, arising from Rashba spin-orbit coupling (SOC), and $D_parallel$ from Dresselhaus SOC. We show that skyrmions become progressively more stable with increasing $D_perp/D_parallel$, extending into the regime of easy-plane anisotropy. We find that the spin texture and topological charge density of skyrmions develops nontrivial spatial structure, with quantized topological charge in a unit cell given by a Chern number. Our results give a design principle for tuning Rashba SOC and magnetic anisotropy to stabilize skyrmions in thin films, surfaces, interfaces and bulk magnetic materials that break mirror symmetry.
The Bose-Einstein condensation (BEC) of the two-dimensional (2D) magnetoexciton-polaritons in microcavity, when the Landau quantization of the electron and hole states accompanied by the Rashba spin-orbit coupling plays the main role, were investigated. The Landau quantization levels of the 2D heavy holes with nonparabolic dispersion law and third order chirality terms both induced by the external electric field perpendicular to the semiconductor quantum well as the strong magnetic field B gives rise to the nonmonotous dependence on B of the magnetoexciton energy levels and of the polariton energy branches. The Hamiltonian describing the Coulomb electron - electron and the electron - radiation interactions was expressed in terms of the two-particle integral operators such as the density operators $hat{rho}(vec{Q})$ and $hat{D}(vec{Q})$ representing the optical and the acoustical plasmons and the magnetoexciton creation and annihilation operators $Psi_{ex}^{dagger}({{vec{k}}_{||}}),Psi_{ex}^{{}}({{vec{k}}_{||}})$ with in - plane wave vectors ${{vec{k}}_{||}}$ and $vec{Q}$. The polariton creation and annihilation operators $L_{ex}^{dagger}({{vec{k}}_{||}}),L_{ex}^{{}}({{vec{k}}_{||}})$ were introduced using the Hopfield coefficients and neglecting the antiresonant terms because the photon energies exceed the energy of the cavity mode. The BEC of the magnetoexciton - polariton takes place on the lower polariton branch in the point ${{vec{k}}_{||}}=0$ with the quantized value of the longitudinal component of the light wave vector, as in the point of the cavity mode.
We consider the Higgs mode at nonzero momentum in superconductors and demonstrate that in the presence of Rashba spin-orbit coupling, it couples linearly with an external exchange field. The Higgs-spin coupling dramatically modifies the spin susceptibility near the superconducting critical temperature and consequently enhances the spin pumping effect in a ferromagnetic insulator/superconductor bilayer system. We show that this effect can be detected by measuring the magnon-induced voltage generated by the inverse spin Hall effect.
The regime of strong light-matter coupling is typically associated with weak excitation. With current realizations of cavity-QED systems, strong coupling may persevere even at elevated excitation levels sufficient to cross the threshold to lasing. In the presence of stimulated emission, the vacuum-Rabi doublet in the emission spectrum is modified and the established criterion for strong coupling no longer applies. We provide a generalized criterion for strong coupling and the corresponding emission spectrum, which includes the influence of higher Jaynes-Cummings states. The applicability is demonstrated in a theory-experiment comparison of a few-emitter quantum-dot--micropillar laser as a particular realization of the driven dissipative Jaynes-Cummings model. Furthermore, we address the question if and for which parameters true single-emitter lasing can be achieved, and provide evidence for the coexistence of strong coupling and lasing in our system in the presence of background emitter contributions.
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