Abstract
Cuprous oxide (Cu₂O) has recently been proposed as a promising solid-state host for excitonic Rydberg states with large principal quantum numbers (n), whose exaggerated wavefunction sizes (∝ n²) facilitate gigantic dipole-dipole (∝ n⁴) and van der Waals (∝ n¹¹) interactions, making them an ideal basis for solid-state quantum technology. Synthetic, thin-film Cu₂O 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 Cu₂O 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.