Quantum Dynamics Simulations of Exciton Polariton Transport

Recent experiments have shown that exciton transport can be significantly enhanced through hybridization with confined photonic modes in a cavity. The light-matter hybridization generates exciton-polariton (EP) bands, whose group velocity is significantly larger than the excitons. Dissipative mechanisms that affect the constituent states of EPs, such as exciton-phonon coupling and cavity loss, have been observed to reduce the group velocities in experiments. To elucidate the impacts of these dissipative mechanisms on polariton transport, we developed an efficient quantum dynamics approach that allows us to directly simulate polariton transport under the collective coupling regime and beyond long-wavelength approximation. Our numerical results suggest a renormalization of the group velocities with stronger exciton-phonon coupling strengths and a smaller Q-factor. We observe the transition from ballistic to diffusive propagation as well as the quality-factor-dependent behavior of the transient mean square displacement, agreeing well with the recent experimental measurements.