Cavity-induced exciton localisation and polariton blockade in two-dimensional semiconductors coupled to an electromagnetic resonator

Abstract

Recent experiments have demonstrated strong light-matter coupling between electromagnetic nanoresonators and pristine sheets of two-dimensional semiconductors, and it has been speculated whether these systems can enter the quantum regime operating at the few-polariton level. To address this question, we present a first-principles microscopic quantum theory for the interaction between excitons in an infinite sheet of two-dimensional material and a localised electromagnetic resonator. We find that the light-matter interaction breaks the symmetry of the otherwise translation-invariant system and thereby effectively generates a localised exciton mode, which is coupled to an environment of residual exciton modes. This dissipative coupling increases with tighter lateral confinement, and our analysis reveals this to be a potential challenge in realising nonlinear exciton-exciton interaction. Nonetheless, we predict that polariton blockade due to nonlinear exciton-exciton interactions is well within reach for nanoresonators coupled to transition-metal dichalcogenides, provided that the lateral resonator mode confinement can be sufficiently small that the nonlinearity overcomes the polariton dephasing caused by phonon interactions.

Microscopic theory of exciton and trion polaritons in doped monolayers of transition metal dichalcogenides

“…The presence of such quasiparticles can qualitatively modify the light-matter coupling and completely reshape the polaritonic spectrum 62,63 . Moreover, various nonlinear effects 61,[63][64][65][66][67][68][69][70][71][72] arise from the phase-space filling, hybridization with light exciton-exciton and exciton-electron scattering, which offers a route towards polariton condensation 73 and the emergence of spontaneous coherence in monolayers strongly coupled to light 74 .…”