Rydberg exciton-polaritons in a Cu2O microcavity

Giant Rydberg excitons with principal quantum numbers as high as n = 25 have been observed in cuprous oxide (Cu2O), a semiconductor in which the exciton diameter can become as large as similar to 1 mu m. The giant dimension of these excitons results in excitonic interaction enhancements of orders of magnitude. Rydberg exciton-polaritons, formed by the strong coupling of Rydberg excitons to cavity photons, are a promising route to exploit these interactions and achieve a scalable, strongly correlated solid-state platform. However, the strong coupling of these excitons to cavity photons has remained elusive. Here, by embedding a thin Cu2O crystal into a Fabry-Perot microcavity, we achieve strong coupling of light to Cu2O Rydberg excitons up to n = 6 and demonstrate the formation of Cu2O Rydberg exciton-polaritons. These results pave the way towards realizing strongly interacting exciton-polaritons and exploring strongly correlated phases of matter using light on a chip. Cu2O is a promising platform to host Rydberg exciton-polaritons, where excitons strongly couple to cavity photons, however their realization has been elusive. Here, the authors report Rydberg exciton-polaritons with principal quantum numbers up to n = 6.