Directional Goldstone waves in polariton condensates close to equilibrium
arXiv:1905.12551 · doi:10.1038/s41467-019-13733-x
Abstract
Quantum fluids of light are realized in semiconductor microcavities by exciton-polaritons, solid-state quasi-particles with a light mass and sizeable interactions. Here, we use the microscopic analogue of oceanographic techniques to measure the excitation spectrum of a thermalised polariton condensate. Increasing the fluid density, we demonstrate the transition from a free-particle parabolic dispersion to a linear, sound-like Goldstone mode characteristic of superfluids at equilibrium. Notably, we show that excitations are created with a definite direction with respect to the condensate, analogous to how a sea breeze develops surface waves aligned with the wind. These results reveal the effect of asymmetric pumping on the collective excitations of a condensate. Furthermore, we measure the critical sound speed for polariton superfluids close to equilibrium.
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- Spontaneous coherence in spatially extended photonic systems: Non-Equilibrium Bose-Einstein condensation
- Onset of vortex clustering and inverse energy cascade in dissipative quantum fluids
- Fully quantum scalable description of driven dissipative lattice models
- Low-energy collective oscillations and Bogoliubov sound in an exciton-polariton condensate
- Non-equilibrium Berezinskii-Kosterlitz-Thouless transition in driven-dissipative condensates
- Modified Bose-Einstein condensation in an optical quantum gas
- Bogoliubov excitations of a polariton condensate in dynamical equilibrium with an incoherent reservoir
- Bogoliubov excitations driven by thermal lattice phonons in a quantum fluid of light
- Finite-temperature Hatree-Fock-Bogoliubov theory for exciton-polaritons
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- Ground and excited states of coupled exciton liquids in electron-hole quadrilayers
- Dark and thermal reservoir contributions to polariton sound velocity
- Collective excitations of exciton-polariton condensates in a synthetic gauge field