Physical Review Research (Dec 2020)

Interferences between Bogoliubov excitations in superfluids of light

  • Quentin Fontaine,
  • Pierre-Élie Larré,
  • Giovanni Lerario,
  • Tom Bienaimé,
  • Simon Pigeon,
  • Daniele Faccio,
  • Iacopo Carusotto,
  • Élisabeth Giacobino,
  • Alberto Bramati,
  • Quentin Glorieux

DOI
https://doi.org/10.1103/PhysRevResearch.2.043297
Journal volume & issue
Vol. 2, no. 4
p. 043297

Abstract

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Paraxial fluids of light represent an alternative platform to atomic Bose-Einstein condensates and superfluid liquids for the study of the quantum behavior of collective excitations. A key step in this direction is the precise characterization of the Bogoliubov dispersion relation, as recently shown in two experiments. However, the predicted interferences between the phonon excitations that would be a clear signature of the collective superfluid behavior have not been observed to date. Here, by analytically, numerically, and experimentally exploring the phonon phase velocity, we observe the presence of interferences between counterpropagating Bogoliubov excitations and demonstrate their critical impact on the measurement of the dispersion relation. These results are evidence of a key signature of light superfluidity and provide a characterization tool for quantum simulations with photons.