Strong photon interactions from weakly interacting particles

TL;DR

This paper demonstrates a resonant process in three-level systems that significantly enhances polariton interactions, paving the way for advanced quantum nonlinear optics across various physical platforms.

Contribution

It uncovers a resonant mechanism that boosts dark-state polariton interactions beyond the limitations of their matter constituents.

Findings

Effective interactions are much larger than matter interactions.

Resonant process enhances polariton interactions by several orders of magnitude.

Applicable to atomic gases, semiconductors, and 2D materials.

Abstract

The hybridization of light and matter excitations in the form of polaritons has enabled major advances in understanding and controlling optical nonlinearities. Entering the quantum regime of strong interactions between individual photons has however remained challenging since the strength of achievable polariton interactions is typically limited by the available interactions in the material. Here, we investigate collisions between dark-state polaritons in three-level systems and discover a resonant process that yields effective interactions, which are much larger than the underlying interaction between their matter constituents. We systematically investigate the underlying mechanism and demonstrate a substantial enhancement of polariton interactions by several orders of magnitude. This suggests a promising approach to quantum nonlinear optics in a range of physical settings, from atomic gases to excitons in semiconductors and two-dimensional bilayer materials.