Transport regimes for exciton polaritons in disordered microcavities

Light-matter coupling in a planar optical cavity substantially modifies the transport regimes in the system in the presence of a short-range excitonic disorder. Based on a master equation for a resonantly coupled exciton-photon system, and treating disorder scattering in the Born-Markov approximation, we demonstrate the onset of ballistic and diffusive transport regimes in the limits of weak and strong disorder, respectively. We show that transport parameters governing the crossover between these two regimes strongly depend on the parameters characterizing light-matter coupling, in particular Rabi energy and detuning between excitonic and photonic modes. The presented theory agrees with recent experimental data on transport in disordered organic microcavities.