Polaron-polariton interactions mediated by an electron gas

We study quasiparticle interactions between exciton-polaritons mediated by an electron gas in a two-dimensional semiconductor inside a microcavity. To this end, we employ a microscopic many-body theory combined with Landau’s quasiparticle framework. We show the presence of attractive interactions between polaritons that stem from the exchange of particle-hole excitations mediated by the electron gas. Besides, the excess of electrons can create bound-states, the so-called trions, that interact with the polaritons by the exchange of an electron, and can be either repulsive or attractive depending on the specific polariton branch. These mediated interactions are intrinsic to the quasiparticles, present in the absence of light, and can be tuned by either the light-matter detuning or the electron density. The combination of attractive and repulsing effects could pave the way to controllable non-lineal polaritonic components.