Quantum confined Rydberg excitons in Cu$_2$O nanoparticles

TL;DR

This study investigates quantum confinement effects on Rydberg excitons in Cu$_2$O nanoparticles, revealing how confinement alters exciton properties and providing insights for quantum technology applications.

Contribution

It demonstrates the observation of Rydberg excitons in Cu$_2$O nanoparticles and explains the impact of quantum confinement on their spectral properties.

Findings

Rydberg excitons observed up to n=12 in bulk and n=6 in nanoparticles

Exciton transition broadening and oscillator strength reduction due to confinement

Quantum confinement effects explained by modified exciton states

Abstract

The quantum confinement of Rydberg excitons is an important step towards exploiting their large nonlinearities for quantum applications. We observe Rydberg excitons in natural nanoparticles of Cu$_2$O. We resolve up to the principal quantum number $n=12$ in a bulk Cu$_2$O crystal and up to $n=6$ in nanoparticles extracted from the same crystal. The exciton transitions in nanoparticles are broadened and their oscillator strengths decrease as $\propto n^{-4}$ compared to those in the bulk (decreasing as $\propto n^{-3}$). We explain our results by including the effect of quantum confinement of exciton states in the nanoparticles. Our results provide an understanding of the physics of Cu$_2$O Rydberg excitons in confined dimensions.