Highly-Excited Rydberg Excitons in Synthetic Thin-Film Cuprous Oxide

TL;DR

This study demonstrates the spectroscopic observation of high principal quantum number Rydberg excitons in synthetic thin-film Cu${}_2$O at elevated temperatures, highlighting their potential for scalable quantum technologies.

Contribution

First spectroscopic analysis of Rydberg excitons up to n=7 in synthetic Cu${}_2$O thin films at high temperatures, advancing solid-state quantum device development.

Findings

Observed Rydberg excitons up to n=7 at 150 K

Demonstrated excitonic properties at powers up to 2 mW

Showed potential for on-chip quantum device integration

Abstract

Cuprous oxide (Cu${}_2$O) has recently been proposed as a promising solid-state host for excitonic Rydberg states with large principal quantum numbers ($n$), whose exaggerated wavefunction sizes ($\propto n^2)$ facilitate gigantic dipole-dipole ($\propto n^4$) and van der Waals ($\propto n^{11}$) interactions, making them an ideal basis for solid-state quantum technology. Synthetic, thin-film Cu${}_2$O samples are of particular interest because they can be made defect-free via carefully controlled fabrication and are, in principle, suitable for the observation of extreme single-photon nonlinearities caused by the Rydberg blockade. Here, we present spectroscopic absorption and photoluminescence studies of Rydberg excitons in synthetic Cu${}_2$O grown on a transparent substrate, reporting yellow exciton series up to $n = 7$. We perform these studies at powers up to 2 mW and temperatures up to 150 K, the highest temperature where Rydberg series can be observed. These results open a new portal to scalable and integrable on-chip Rydberg-based quantum devices.