Giant Rydberg excitons in Cu$_{2}$O probed by photoluminescence excitation spectroscopy

TL;DR

This paper demonstrates the use of photoluminescence excitation spectroscopy to probe giant Rydberg excitons in cuprous oxide at ultra-low temperatures, revealing states up to n=30 with potential for quantum applications.

Contribution

It introduces a novel spectroscopic method to study transition probabilities of Rydberg excitons in cuprous oxide, extending the understanding of their properties at high principal quantum numbers.

Findings

Giant Rydberg excitons observed up to n=30

Excitons with diameters up to 3 micrometers

Method enables probing of excitonic transition probabilities

Abstract

Rydberg excitons are, with their ultrastrong mutual interactions, giant optical nonlinearities, and very high sensitivity to external fields, promising for applications in quantum sensing and nonlinear optics at the single-photon level. To design quantum applications it is necessary to know how Rydberg excitons and other excited states relax to lower-lying exciton states. Here, we present photoluminescence excitation spectroscopy as a method to probe transition probabilities from various excitonic states in cuprous oxide, and we show giant Rydberg excitons at $T=38$ mK with principal quantum numbers up to $n=30$, corresponding to a calculated diameter of 3 $\mu$m.