  In recent years, a rigorous quantum mechanical model for the interaction
between light and macroscopic dispersive, lossy dielectrics has emerged
-macroscopic QED- allowing the application of the usual methods of quantum
field theory. Here, we apply time dependent perturbation theory to a general
class of problems involving time dependent lossy, dispersive dielectrics. The
model is used to derive polariton excitation rates in three illustrative cases,
including that of a travelling Gaussian perturbation to the susceptibility of
an otherwise infinite homogeneous dielectric, motivated by recent experiments
on analogue Hawking radiation. We find that the excitation rate is increased
when the wave--vector and frequency of each polariton in the pair either
satisfies (or nearly satisfies) the dispersion relation for electromagnetic
waves, or is close to a material resonance.
