Opto-valleytronic moiré polaritons

ended

The emerging field of opto-valleytronics based on two-dimensional (2D) transition metal dichalcogenides (TMDs) has the potential to revolutionize quantum information processing by enabling all-optical quantum photonic circuits with nonlinear and non-reciprocal devices, such as optical switches and isolators. Such devices are inherently difficult to realize because photons generally do not interact and flow in both directions due to time-reversal symmetry. In this action, I propose to develop novel optical microcavities with embedded TMD heterostructures to achieve photon-photon interaction and directional light propagation. A small twist angle between TMD heterobilayers gives rise to hybrid moiré excitons exhibiting a permanent dipole moment in addition to increased lifetimes and oscillator strengths. Strongly coupled to a microcavity, moiré polaritons emerge with valley-contrasting dipolar optical selection rules. Moiré polaritons exhibit optical nonlinearities induced by the moiré potential. Based on all this, the overriding research objective of the project 2DValley is to develop and investigate novel opto-valleytronic devices utilizing valley-polarized moiré polaritons. To achieve this goal, I will first develop gate-tunable moiré polaritons by studying hybrid moiré excitons in cryogenic optical spectroscopy and then embedding them into optical microcavities. I propose to lift the valley degeneracy of moiré polaritons with an external magnetic field, providing control over the valley degree of freedom. Finally, I propose to replace the external magnetic field by an internal built-in magnetic field via 2D ferromagnets, which enables unprecedented intrinsic control of the valley degree of freedom by lifting valley degeneracy via magnetic proximity exchange interaction. Such nonlinear and non-reciprocal opto-valleytronic devices would have potential technological and societal impact by increasing information processing speed, volume, and security.