Nonlinear valley phonon scattering under the strong coupling regime

Research efforts of cavity quantum electrodynamics have focused on the manipulation of matter hybridized with photons under the strong coupling regime(1-3). This has led to striking discoveries including polariton condensation(2) and single-photon nonlinearity(3), where the phonon scattering plays a critical role(1-9). However, resolving the phonon scattering remains challenging for its non-radiative complexity. Here we demonstrate nonlinear phonon scattering in monolayer MoS2 that is strongly coupled to a plasmonic cavity mode. By hybridizing excitons and cavity photons, the phonon scattering is equipped with valley degree of freedom and boosted with superlinear enhancement to a stimulated regime, as revealed by Raman spectroscopy and our theoretical model. The valley polarization is drastically enhanced and sustained throughout the stimulated regime, suggesting a coherent scattering process enabled by the strong coupling. Our findings clarify the feasibility of valley-cavity-based systems for lighting, imaging, optical information processing and manipulating quantum correlations in cavity quantum electrodynamics(2,3,10-17).

Automated summary

Nonlinear phonon scattering in monolayer MoS2 strongly coupled to a plasmonic cavity mode has been demonstrated, showing enhanced valley polarization and sustained coherence in the stimulated regime. This suggests the potential of valley-cavity-based systems for various applications in cavity quantum electrodynamics.