Attractive trion-polariton nonlinearity due to Coulomb scattering

TL;DR

This paper provides a theoretical analysis of trion-polariton nonlinearity in 2D materials, revealing an attractive interaction five times stronger than exciton-polaritons, with implications for light-based fluid systems.

Contribution

It introduces a precise three-body Wannier equation approach to evaluate trion-polariton interactions, resolving the trion-trion scattering question and highlighting the attractive nonlinearity.

Findings

Trion-polariton nonlinearity is attractive and significantly stronger than exciton-polariton interactions.

The nonlinearity results from a balance of different Coulomb scattering channels.

Wavefunction overlaps and material parameters critically influence the interaction strength.

Abstract

We theoretically investigate the nonlinearity of trion-polaritons in a two-dimensional material that arises from Coulomb interaction between quasiparticles. To evaluate the interaction constant, we solve a three-body Wannier equation precisely by expanding trion wavefunctions into a Gaussian basis. Using these wavefunctions, we calculate the trion-polariton interaction energies for the exchange processes, resolving the outstanding question of trion-trion scattering. We find that the nonlinearity is the result of the competition between different scattering channels. Such a cancellation effect is sensitive to wavefunction overlaps and depends on material parameters. Most importantly, our result shows that the nonlinear interaction between trion-polaritons is attractive, and is fivefold stronger than exciton-polariton interaction. Our work thus describes the regime where trion-polaritons offer the prospects for attractive fluids of light in monolayers of transition metal dichalcogenides.