Nonclassical Light from Exciton Interactions in a Two-Dimensional Quantum Mirror

TL;DR

This paper explores how exciton interactions in a 2D semiconductor monolayer can produce highly non-classical light, enabling robust single-photon switching and correlations for quantum photonics applications.

Contribution

It introduces novel mechanisms for nonlinear optical effects in 2D excitonic systems, demonstrating robust non-classical light generation unaffected by typical decoherence.

Findings

Finite-range exciton interactions enable non-classical light.

Electromagnetically induced transparency facilitates single-photon switching.

Photon correlations are resilient to Rydberg-state decoherence.

Abstract

Excitons in a semiconductor monolayer form a collective resonance that can reflect resonant light with extraordinarily high efficiency. Here, we investigate the nonlinear optical properties of such atomistically thin mirrors and show that finite-range interactions between excitons can lead to the generation of highly non-classical light. We describe two scenarios, in which optical nonlinearities arise either from direct photon coupling to excitons in excited Rydberg states or from resonant two-photon excitation of Rydberg excitons with finite-range interactions. The latter case yields conditions of electromagnetically induced transparency and thereby provides an efficient mechanism for single-photon switching between high transmission and reflectance of the monolayer, with a tunable dynamical timescale of the emerging photon-photon interactions. Remarkably, it turns out that the resulting high degree of photon correlations remains virtually unaffected by Rydberg-state decoherence, in excess of non-radiative decoherence observed for ground-state excitons in two-dimensional semiconductors. This robustness to imperfections suggests a promising new approach to quantum photonics at the level of individual photons.