Valley coherent exciton-polaritons in a monolayer semiconductor

• DOI: 10.1038/s41467-018-07249-z
• Publication Date: 2018-11-09T11:48:09Z
• Authors: S. Dufferwiel; T. P. Lyons; D. D. Solnyshkov; A. A. P. Trichet; A. Catanzaro; F. Withers; G. Malpuech; J. M. Smith; K. S. Novoselov; M. S. Skolnick; D. N. Krizhanovskii; A. I. Tartakovskii
• Keywords: Exciton-polaritons; Valleytronics

Two-dimensional transition metal dichalcogenide (TMD) semiconductors provide a unique possibility to access the electronic valley degree of freedom using polarized light, opening way information transfer between distant systems. Excitons with well-defined index (or pseudospin) as well superpositions exciton states can be created light having circular and linear polarization, respectively. However, generated excitons have short lifetimes (ps) are also subject electron-hole exchange interaction leading fast relaxation pseudospin coherence. Here we show that control these processes gained by embedding monolayer WSe$_2$ in an optical microcavity, where part-light-part-matter exciton-polaritons formed strong light-matter coupling regime. We demonstrate initialization coherent polariton populations, exhibiting luminescence polarization up 3 times higher than excitons. further evolution coherence Faraday magnetic field rotate angle defined exciton-cavity-mode detuning, which exceeds rotation bare exciton. This work provides insight into decoherence mechanisms TMDs demonstrates potential for engineering dynamics embedded photonic structures.