Cavity control of Excitons in two dimensional Materials

TL;DR

This paper introduces a first-principles, non-perturbative framework for controlling and simulating exciton-polaritons in 2D materials via quantum cavity embedding, revealing tunable spectral features and excitonic inversions.

Contribution

It develops a novel ab-initio, quantum-electrodynamical approach to model exciton-polaritons in 2D materials and heterostructures, enabling control over optical spectra through cavity and dielectric environment manipulation.

Findings

Reordering and mixing of bright and dark excitons spectral features.

Inversion of intra and interlayer excitonic resonances in heterostructures.

Cavity light-matter coupling depends strongly on dielectric environment.

Abstract

We propose a robust and efficient way of controlling the optical spectra of two-dimensional materials and van der Waals heterostructures by quantum cavity embedding. The cavity light-matter coupling leads to the formation of exciton-polaritons, a superposition of photons and excitons. Our first principles study demonstrates a reordering and mixing of bright and dark excitons spectral features and in the case of a type II van-der-Waals heterostructure an inversion of intra and interlayer excitonic resonances. We further show that the cavity light-matter coupling strongly depends on the dielectric environment and can be controlled by encapsulating the active 2D crystal in another dielectric material. Our theoretical calculations are based on a newly developed non-perturbative many-body framework to solve the coupled electron-photon Schr\"odinger equation in a quantum-electrodynamical extension of the Bethe-Salpeter approach. This approach enables the ab-initio simulations of exciton-polariton states and their dispersion from weak to strong cavity light-matter coupling regimes. Our method is then extended to treat van der Waals heterostructures and encapsulated 2D materials using a simplified Mott-Wannier description of the excitons that can be applied to very large systems beyond reach for fully ab-initio approaches.