On the nature of polariton transport in a Fabry-Perot Cavity

Fabry-Perot microcavities can strongly enhance interactions between light and molecules, leading to the formation of hybrid light-matter states known as polaritons. Polaritons possess much smaller effective masses and much larger group velocities when the molecules are resonant with cavity modes that have finite (non-zero) in-plane wavevectors, giving rise to the possibilities of long-range and ultrafast ballistic transport. In this paper, we present results of numerical simulations of the ultrafast ballistic transport phenomenon in real space and time during and after initialization with a short, spatially localized pulse. We find that the transport of the molecular excitons as induced by the external light field is synchronized with the evolution of the enhanced and localized electromagnetic field inside the cavity. Moreover, the synchronized transport rate is in good agreement with the group velocities predicted from a calculated dispersion relation across a wide range of frequencies. These simulations provide an intuitive tool for understanding the collective motion of light and excitons and helps to better understand how experimental observations of polaritons should be interpreted.