Highly-excited Rydberg excitons in synthetic thin-film cuprous oxide


Cuprous oxide ($\hbox {Cu}{}_2\hbox {O}$) has recently emerged as a promising material in solid-state quantum technology, specifically for its excitonic Rydberg states characterized by large principal quantum numbers (n). The significant wavefunction size of these highly-excited states (proportional to $n^2$) enables strong long-range dipole-dipole (proportional to $n^4$) and van der Waals interactions (proportional to $n^{11}$). Currently, the highest-lying Rydberg states are found in naturally occurring $\hbox {Cu}_2\hbox {O}$. However, for technological applications, the ability to grow high-quality synthetic samples is essential. The fabrication of thin-film $\hbox {Cu}{}_2\hbox {O}$samples is of particular interest as they hold potential for observing extreme single-photon nonlinearities through the Rydberg blockade. Nevertheless, due to the susceptibility of high-lying states to charged impurities, growing synthetic samples of sufficient quality poses a substantial challenge. This study successfully demonstrates the CMOS-compatible synthesis of a $\hbox {Cu}{}_2\hbox {O}$thin film on a transparent substrate that showcases Rydberg excitons up to $n = 8$which is readily suitable for photonic device fabrications. These findings mark a significant advancement towards the realization of scalable and on-chip integrable Rydberg quantum technologies.

Scientific Reports