Planar microcavities with embedded semiconducting materials can host exciton polaritons - hybrid lightmatter quasiparticles consisting of excitons (bound electron-hole pairs) and photons. The formation of polaritons occurs when the energy exchange rate between the excitons and the cavity photons, is sufficiently large. By taking advantage of the interactions between the excitonic component one can create an interaction driven macroscopically coherent quantum state, i.e., a polariton condensate, on a microchip at room temperature. This could potentially enable dissipationless electronics and low-threshold polariton lasers. Atomically-thin transition metal dichalcogenide crystals (monolayer TMDCs) are promising materials for room temperature polaritonics. In this talk, I will demonstrate various methods for engineering the properties of WS2 polaritons in high-quality all-dielectric planar microcavities. These techniques allow us to observe ballistic transport in monolayer WS2 at room temperature, to achieve strong spatial confinement for the polaritons and enhance their macroscopic coherence, and to observe the transition between neutral and charged polaritons without applying an external gate voltage. Our approach critically relies on the novel passivation and protection technology for monolayer WS2 based on ultrathin Ga2O3 glass. Further, I will introduce a new concept of non-Hermitian dispersion engineering by employing dissipative coupling between the excitons and photons, and demonstrate how to realize polaritons with a negative mass. Presented experimental techniques could also be applied to other exciton hosting materials, e.g., perovskites, as well as for integrating TMDCs into different photonic resonators, e.g., photonic crystals with high quality factor resonances.

Dr. Matthias Wurdack is a Postdoctoral Fellow in the Polariton BEC group, DQST, RSPhys and the ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET). He received PhD in Physics from ANU for his work on exciton polaritons in atomically thin semiconductors. In his current role, Dr. Wurdack is leading the research on exciton polaritons in 2D materials across multiple nodes of FLEET, with the long-term goal to enable future polaritonic devices. He also had leading roles in the ANU SPIE and Optica student chapters, FLEET, and the RSPhys HDR cohort. He won multiple awards, including the John Carver Prize and AIP Award for Postgraduate Excellence in 2020, is a finalist of the 2023 Schmidt Science Fellows cohort and represented Australia at the 71st Lindau Nobel Laurate Meeting.

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