Exciton-polaritons in semiconductor microcavities exhibit large two-body interactions that, thanks to ever refined nanotechnology techniques, are getting closer and closer to the quantum regime where single-photon nonlinearities start being relevant. To foster additional progress in this direction, in this work we experimentally investigate the microscopic mechanism driving polariton-polariton interactions. We measure the dispersion relation of the collective excitations that are thermally generated on top of a coherent fluid of interacting lower-polaritons. By comparing the measurements with the Bogoliubov theory over both the lower and upper polariton branches simultaneously, we find that polariton-polariton interactions stem dominantly from a mechanism of saturation of the exciton oscillator strength.
@article{arxiv.2501.07899,
title = {Excitonic oscillator-strength saturation dominates polariton-polariton interactions},
author = {Maxime Richard and Irénée Frérot and Sylvain Ravets and Jacqueline Bloch and Carlos Anton-Solanas and Ferdinand Claude and Yueguang Zhou and Martina Morassi and Aristide Lemaître and Iacopo Carusotto and and Anna Minguzzi},
journal= {arXiv preprint arXiv:2501.07899},
year = {2025}
}