Exploring polariton quantum phases and chemical reactivity under strong light–matter coupling

Abstract

Strong light–matter coupling in optical cavities enables the formation of hybrid quasiparticles known as polaritons, which provide new opportunities to control quantum states and chemical reactivity. Among these, solid-state exciton–polariton systems have shown that strong coupling can lead to the emergence of rich collective quantum phases in hybrid light–matter systems. In parallel, vibrational polaritons, created by coupling molecular vibrational transitions with cavity photon modes, have recently emerged as a powerful platform for modifying ground-state reaction landscapes, altering reaction rates, and enabling new mechanistic pathways even in the absence of external illumination. This dissertation demonstrates that carefully designed light–matter interactions can give rise to new physical phenomena and establish a conceptual foundation for utilizing controlled coupling strategies to manipulate both quantum phases of matter and chemical transformations at room temperature. Specifically, topological polariton condensation was demonstrated in a valley Hall photonic lattice integrated with a single-crystal CsPbCl₃ microcavity, where coherent condensates propagate along topological edge states at room temperature. A room-temperature polariton supersolid phase was realized by coupling CsPbCl₃ microplates with a photonic nanostructure that supports hybrid light–matter modes. In addition, vibrational strong coupling was employed to investigate cavity-modified ground state chemical reactivity, where modification of reaction rates was observed in an alcoholysis reaction. In summary, this work establishes hybrid light–matter systems as a versatile platform for exploring emergent quantum phases and cavity-modified chemistry, opening new opportunities for controlling both collective quantum phenomena and chemical dynamics through engineered photonic environments.