  As a quantum analog of Cherenkov radiation, an inertial photon detector
moving through a medium with constant refractive index $n$ may perceive the
electromagnetic quantum fluctuations as real photons if its velocity $v$
exceeds the medium speed of light $c/n$. For dispersive Hopfield type media, we
find this Ginzburg effect to extend to much lower $v$ because the phase
velocity of light is very small near the medium resonance. In this regime,
however, dissipation effects become important. Via an extended Hopfield model,
we present a consistent treatment of quantum fluctuations in dispersive and
dissipative media and derive the Ginzburg effect in such systems. Finally, we
propose an experimental test.
