Valley-selective optical Stark effect of exciton-polaritons in a monolayer semiconductor.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34312389.
- Also identified by DOI 10.1038/s41467-021-24764-8 and PMC identifier 8313563.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Selective breaking of degenerate energy levels is a well-known tool for coherent manipulation of spin states. Though most simply achieved with magnetic fields, polarization-sensitive optical methods provide high-speed alternatives. Exploiting the optical selection rules of transition metal dichalcogenide monolayers, the optical Stark effect allows for ultrafast manipulation of valley-coherent excitons. Compared to excitons in these materials, microcavity exciton-polaritons offer a promising alternative for valley manipulation, with longer lifetimes, enhanced valley coherence, and operation across wider temperature ranges. Here, we show valley-selective control of polariton energies in WS<sub>2</sub> using the optical Stark effect, extending coherent valley manipulation to the hybrid light-matter regime. Ultrafast pump-probe measurements reveal polariton spectra with strong polarization contrast originating from valley-selective energy shifts. This demonstration of valley degeneracy breaking at picosecond timescales establishes a method for coherent control of valley phenomena in exciton-polaritons.