Rotational symmetry breaking on the Rydberg energy spectrum of indirect excitons in diamond studied by terahertz time-domain spectroscopy

We investigated the 1S-2P transitions of the indirect excitons in diamond around 70 meV in the high-frequency terahertz region via time-resolved Lyman spectroscopy. We discovered significant splitting of the 2P levels and attributed it to the rotational-symmetry-breaking effect owing to the cubic crystal environment. The maximum energy separation of 14.9 meV reached 18% of the excitonic Rydberg constant-83.5 +/- 2.9 meV-which deviated from the binding energy of the 1S ground state: 93.3 +/- 2.0 meV. In addition to the anisotropy of the valence bands, we found the impact of the rotational symmetry breaking of the conduction band valleys, which leads to a significant deviation from the case with direct excitons. Detailed knowledge of the ground and excited states of long-lifetime excitons provides an unprecedented opportunity to develop the study of quantum many-body physics and quantum chaos.

Automated summary

Through experimental investigation, significant splitting of the 2P levels in the 1S-2P transitions of indirect excitons in diamond was discovered, attributed to the rotational symmetry breaking effect. This splitting led to a deviation in energy between the excitonic Rydberg constant and the 1S ground state, as well as an impact from the rotational symmetry breaking of the conduction band valleys.