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Directional Goldstone waves in polariton condensates close to equilibrium.

ABSTRACT: Quantum fluids of light are realized in semiconductor microcavities using 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 reveal the effect of an asymmetric pumping by showing that collective excitations are created with a definite direction with respect to the condensate. Furthermore, we measure the critical sound speed for polariton superfluids close to equilibrium.

SUBMITTER: Ballarini D

PROVIDER: S-EPMC6954190 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Directional Goldstone waves in polariton condensates close to equilibrium.

Ballarini Dario D Caputo Davide D Dagvadorj Galbadrakh G Juggins Richard R Giorgi Milena De M Dominici Lorenzo L West Kenneth K Pfeiffer Loren N LN Gigli Giuseppe G Szymańska Marzena H MH Sanvitto Daniele D

Nature communications 20200110 1

Quantum fluids of light are realized in semiconductor microcavities using 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. Notabl ...[more]

PMID: 31924751

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