  Rydberg excitons, the solid-state counterparts of Rydberg atoms, have sparked
considerable interest in harnessing their quantum application potentials,
whereas a major challenge is realizing their spatial confinement and
manipulation. Lately, the rise of two-dimensional moir\'e superlattices with
highly tunable periodic potentials provides a possible pathway. Here, we
experimentally demonstrate this capability through the observation of Rydberg
moir\'e excitons (XRM), which are moir\'e trapped Rydberg excitons in monolayer
semiconductor WSe2 adjacent to twisted bilayer graphene. In the strong coupling
regime, the XRM manifest as multiple energy splittings, pronounced redshift,
and narrowed linewidth in the reflectance spectra, highlighting their
charge-transfer character where electron-hole separation is enforced by the
strongly asymmetric interlayer Coulomb interactions. Our findings pave the way
for pursuing novel physics and quantum technology exploitation based on the
excitonic Rydberg states.
