Coherent and incoherent dynamics of exciton-polaritons

Abstract

Electronic quantum coherence in molecular systems rarely persists beyond tens of femtoseconds at room temperature, especially at the macroscopic scale. Recent experimental work suggests that coupling molecular or material excitation to confined radiation inside an optical cavity leads to enhanced coherence lifetime, extending to picoseconds at room temperature. We develop new quantum dynamical approaches as well as analytical theoretical frameworks to provide microscopic insights into this phenomenon. Specifically, we develop a microscopic theory to describe polaron polariton dispersion, formed by hybridizing excitons, photons, and phonons, as well as their coherent dynamics inside optical cavities. Using this framework, we show that the entire polaron-polariton system can be described with a band picture despite the phonons breaking translational symmetry. This theory sheds light on the long-lived coherent ballistic motion of exciton-polaritons with high excitonic character that propagate with group velocities lower than expected from pure exciton-polariton bands.