@article{83c9b090113d45f686c0cd25928cc16e,
title = "Valley-selective optical Stark effect of exciton-polaritons in a monolayer semiconductor",
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 WS2 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.",
author = "Trevor LaMountain and Jovan Nelson and Lenferink, {Erik J.} and Amsterdam, {Samuel H.} and Murthy, {Akshay A.} and Hongfei Zeng and Marks, {Tobin J.} and Dravid, {Vinayak P.} and Hersam, {Mark C.} and Stern, {Nathaniel P.}",
note = "Funding Information: This research has primarily been supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award No. DE-SC0012130 (cavity exciton-polaritons) and the Office of Naval Research under grant number N00014-16-1-3055 (ultrafast valley manipulation). This work was also supported by the National Science Foundation under Grant No. DMR-1929356 (2D materials synthesis). S.H.A., T.J.M., and M.C.H. acknowledge support from the National Science Foundation Materials Research Science and Engineering Center (MRSEC) under Grant No. DMR-1720139. This work made use of the Keck-II facility and the NUFAB facility of the Northwestern University NUANCE Center, which has received support from the SHyNE Resource (NSF ECCS-1542205), the IIN, and the Northwestern University MRSEC program (NSF DMR-1720139). J.N. acknowledges support from the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1842165. S.H.A. acknowledges support from the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program. A. A.M. gratefully acknowledges support from the Ryan Fellowship and the IIN at Northwestern University. Publisher Copyright: {\textcopyright} 2021, The Author(s).",
year = "2021",
month = dec,
doi = "10.1038/s41467-021-24764-8",
language = "English (US)",
volume = "12",
journal = "Nature Communications",
issn = "2041-1723",
publisher = "Nature Publishing Group",
number = "1",
}