First principles GW-BSE study of Rydberg excitons in Cu₂O

Excitons in cuprous oxide (Cu₂O) can be classified into different series based on the different band transitions around the Brillouin zone center. The lowest-energy yellow exciton series arises from dipole-forbidden transitions and experiments have resolved Rydberg excitons in this series with principal quantum number (n) as high as 30. The ability to resolve these spatially massive excitons, combined with their narrow line widths, positions them as candidates for quantum sensing applications. Using first-principles GW-Bethe Salpeter equation (GW-BSE) calculations we study the optical selection rules and the variation of exciton radius and energy as a function of n. We also address well-known challenges in studying excited states in Cu₂O related to spurious band reordering in single-shot G0W0 calculations.