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RESEARCH PRODUCT

Phonoritons as Hybridized Exciton-Photon-Phonon Excitations in a Monolayer h -BN Optical Cavity

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[EN] A phonoriton is an elementary excitation that is predicted to emerge from hybridization between exciton, phonon, and photon. Besides the intriguing many-particle structure, phonoritons are of interest as they could serve as functional nodes in devices that utilize electronic, phononic, and photonic elements for energy conversion and thermal transport applications. Although phonoritons are predicted to emerge in an excitonic medium under intense electromagnetic wave irradiation, the stringent condition for their existence has eluded direct observation in solids. In particular, on-resonance, intense pumping schemes have been proposed, but excessive photoexcitation of carriers prevents optical detection. Here, we theoretically predict the appearance of phonoritonic features in monolayer hexagonal boron nitride (h-BN) embedded in an optical cavity. The coherent superposition nature of phonoriton states is evidenced by the hybridization of exciton-polariton branches with phonon replicas that is tunable by the cavity-matter coupling strength. This finding simultaneously provides an experimental pathway for observing the predicted phonoritons and opens a new avenue for tuning materials properties. We thank Emre Ergecen for constructive discussions. We acknowledge financial support from the European Research Council (Grant No. ERC-2015-AdG-694097). Grupos Consolidados (Grant No. IT1249-19), and the Cluster of Excellence “CUI: Advanced Imaging of Matter” of the Deutsche Forschungsgemeinschaft (DFG)—EXC 2056— Project ID No. 390715994. The Flatiron Institute is a division of the Simons Foundation. S. L. acknowledges support from the Alexander von Humboldt foundation. Work at MIT was supported by the US Department of Energy, BES DMSE and by the Gordon and Betty Moore Foundations EPiQS Initiative Grant No. GBMF9459.