Polariton-polariton scattering: exact results through a novel approach

TL;DR

This paper introduces an exact microscopic approach to polariton-polariton scattering, revealing a photon-assisted exchange process that differs from conventional models and significantly impacts transition rates, especially in microcavities.

Contribution

It develops a novel composite-exciton many-body theory to accurately analyze polariton scattering, highlighting a fundamental photon-assisted exchange process.

Findings

Photon-assisted exchange dominates in certain scattering regimes.

Transition rates are significantly enhanced in microcavities.

Results differ from conventional boson-mapping approaches.

Abstract

We present a fully microscopic approach to the transition rate of two exciton-photon polaritons. The non-trivial consequences of the polariton composite nature -- here treated exactly through a development of our composite-exciton many-body theory -- lead to results noticeably different from the ones of the conventional approaches in which polaritons are mapped into elementary bosons. Our work reveals an appealing fundamental scattering which corresponds to a photon-assisted exchange -- in the absence of Coulomb process. This scattering being dominant when one of the scattered polaritons has a strong photon character, it should be directly accessible to experiment. In the case of microcavity polaritons, it produces a significant enhancement of the polariton transition rate when compared to the one coming from Coulomb interaction. This paper also contains the crucial tools to securely tackle the many-body physics of polaritons, in particular towards its possible BEC.