Detection of both optical polarization and coherence transfers to excitonic valley states in CVD-grown monolayer MoS₂

We experimentally demonstrate the generation and detection of both excitonic valley polarization and coherence in CVD-grown monolayer MoS₂ under nearly resonant excitation in polarized photoluminescence. By circular and linear photoexcitation close to the A-exciton energy, where the excitation energy is 37 meV above the A-exciton energy, 54% and 32% of valley polarization and coherence, respectively, are observed at T = 20 K. By tuning the optical polarization and the polarization plane of photoexcitation, valley polarization and its coherence are systematically controlled. This indicates the coherent control of an excitonic valley two-level system, an important step for valley quantum information.