Scientific Results

Dispersion relation of the collective excitations in a resonantly driven polariton fluid

Year: 2019

Authors: Stepanov P., Amelio I., Rousset JG., Bloch J., Lemaitre A., Amo A., Minguzzi A., Carusotto I., Richard M.

Autors Affiliation: Univ Grenoble Alpes, CNRS, Grenoble INP, Inst Neel, F-38000 Grenoble, France; Univ Trento, CNR, INO, BEC Ctr, I-38123 Povo, Italy; Univ Trento, Dipartimento Fis, I-38123 Povo, Italy; Univ Warsaw, Fac Phys, Inst Expt Phys, Ul Pasteura 5, PL-02093 Warsaw, Poland; Univ Paris Saclay, Univ Paris Sud, CNRS, Ctr Nanosci & Nanotechnol,C2N Marcoussis, F-91460 Marcoussis, France
Show more [ 6 ] Univ Lille, CNRS, Phys Lasers Atomes & Mol, F-59000 Lille, France
Show more [ 7 ] Univ Grenoble Alpes, CNRS, LPMMC, F-38000 Grenoble, France

Abstract: Exciton-polaritons in semiconductor microcavities constitute the archetypal realization of a quantum fluid of light. Under coherent optical drive, remarkable effects such as superfluidity, dark solitons or the nucleation of vortices have been observed, and can be all understood as specific manifestations of the condensate collective excitations. In this work, we perform a Brillouin scattering experiment to measure their dispersion relation omega(k) directly. The results, such as a speed of sound which is apparently twice too low, cannot be explained upon considering the polariton condensate alone. In a combined theoretical and experimental analysis, we demonstrate that the presence of an excitonic reservoir alongside the polariton condensate has a dramatic influence on the characteristics of the quantum fluid, and explains our measurement quantitatively. This work clarifies the role of such a reservoir in polariton quantum hydrodynamics. It also provides an unambiguous tool to determine the condensateto-reservoir fraction in the quantum fluid, and sets an accurate framework to approach ideas for polariton-based quantum-optical applications.

Journal/Review: NATURE COMMUNICATIONS

Volume: 10      Pages from: 3869  to: 3869

KeyWords: BOSE-EINSTEIN CONDENSATION; QUANTIZED VORTICES; LIQUID-HELIUM; SOLITONS
DOI: 10.1038/s41467-019-11886-3

Citations: 3
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