Electromagnetically induced transparency with Cu$_2$O excitons in the presence of phonon coupling

TL;DR

This paper demonstrates how two-photon EIT can suppress phonon-induced absorption background in Rydberg excitons of Cu$_2$O, enabling control of strong particle interactions for nonlinear optical applications.

Contribution

It introduces a microscopic theory showing how two-photon EIT can separate Rydberg excitations from phonon background in Cu$_2$O, overcoming a major obstacle in solid-state exciton control.

Findings

Two-photon EIT can suppress phonon absorption background.

The theory predicts conditions for effective Rydberg exciton control.

Potential for enhanced nonlinear optical applications.

Abstract

Highly excited Rydberg states of excitons in Cu$_2$O semiconductors provide a promising approach to explore and control strong particle interactions in a solid-state environment. A major obstacle has been the substantial absorption background that stems from exciton-phonon coupling and lies under the Rydberg excitation spectrum, weakening the effects of exciton interactions. Here, we demonstrate that two-photon excitation of Rydberg excitons under conditions of electromagnetically induced transparency (EIT) can be used to control this background. Based on a microscopic theory that describes the known single-photon absorption spectrum, we analyze the conditions under which two-photon EIT permits separating the optical Rydberg excitation from the phonon-induced absorption background, and even suppressing it entirely. Our findings thereby pave the way for the exploitation of Rydberg blockade with Cu$_2$O excitons in nonlinear optics and other applications.