Nonlinear optical response of resonantly driven polaron-polaritons

TL;DR

This paper investigates how electron interactions influence the nonlinear optical properties of polaron-polaritons in 2D semiconductors, revealing regimes with hysteresis effects that are experimentally accessible.

Contribution

It introduces a non-perturbative many-body and non-equilibrium theoretical framework to analyze polaron-polaritons, highlighting electron density effects on their nonlinear behavior.

Findings

Identification of stable and unstable polaron-polariton regimes

Prediction of hysteresis effects with electron density variation

Strong nonlinearities due to electron-electron interactions

Abstract

Exciton polaritons in two-dimensional semiconductors inside microcavities are powerful platforms to explore hybrid light-matter quantum systems. Here, we study a macroscopic coherent population of the lowest energy state of polaron-polaritons, which are quasiparticles formed by the dressing of exciton polaritons by particle-hole excitations in a surrounding electron gas. Using a non-perturbative many-body theory to describe exciton-electron correlations combined with a non-equilibrium theory for the macroscopically populated state, we show that the electrons strongly affect the collective properties of the polaron-polaritons. This stems from the dependence of the polaron-polariton energy and the interaction between them on the electron density, which leads to strong nonlinearities. We identify stable and unstable regimes of the polaron-polaritons by calculating its excitation spectrum, and show that they result in prominent hysteresis effects when the electron density is varied. Our results should be readily observable using present experimental technology.