Excitonic oscillator-strength saturation dominates polariton-polariton interactions

TL;DR

This paper investigates the microscopic mechanism behind polariton-polariton interactions in semiconductor microcavities, revealing that excitonic oscillator-strength saturation is the dominant factor influencing these interactions.

Contribution

The study provides experimental evidence that excitonic oscillator-strength saturation primarily drives polariton-polariton interactions, advancing understanding of quantum nonlinearities in microcavity polaritons.

Findings

Interactions are dominated by excitonic oscillator-strength saturation.

Measured dispersion relations align with Bogoliubov theory predictions.

The mechanism is consistent across both lower and upper polariton branches.

Abstract

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.