We present a comprehensive study of the exciton wave
packet evolution
in disordered lossless polaritonic wires. Our simulations reveal signatures
of ballistic, diffusive, and subdiffusive exciton dynamics under strong
light–matter coupling and identify the typical time scales
associated with the transitions between these qualitatively distinct
transport phenomena. We determine optimal truncations of the matter
and radiation subsystems required for generating reliable time-dependent
data from computational simulations at an affordable cost. The time
evolution of the photonic part of the wave function reveals that many
cavity modes contribute to the dynamics in a nontrivial fashion. Hence,
a sizable number of photon modes is needed to describe exciton propagation
with a reasonable accuracy. We find and discuss an intriguingly common
lack of dominance of the photon mode on resonance with matter in both
the presence and absence of disorder. We discuss the implications
of our investigations for the development of theoretical models and
analysis of experiments where coherent intermolecular energy transport
and static disorder play an important role.