Interplay between Rydberg excitons and moiré superlattices

The Rydberg excitons are the excited Coulomb-bound states of electron-hole pairs. Their solid-state nature, in conjunction with the large dipole moments and enhanced interactions with the surroundings, makes them promising candidates for a wide range of applications. Here we study the optical response of Rydberg excitons in a monolayer semiconductor WSe2 placed on twisted bilayer graphene (TBG). First, the TBG with gate-tunable periodic potentials gives a pathway for spatial confinement and manipulation of Rydberg excitons. We experimentally demonstrate this capability through the spectroscopic evidence of Rydberg moiré excitons. Second, the optical response of Rydberg excitons in WSe2 could serve as a delicate dielectric sensor to probe the density-of-state evolution in the neighboring TBG near the magic angle, allowing us to reveal novel physics that combines both strong electronic correlations and non-trivial band topology.