  In this article we provide a a general analysis of canonical quantization for
polaritons in dispersive and dissipative electromagnetic media. We compare
several approaches based either on the Huttner Barnett model [B. Huttner, S. M.
Barnett, Phys. Rev. A \textbf{46}, 4306 (1992)] or the Green function, Langevin
noise method [T. Gruner, D.-G. Welsch, Phys. Rev. A \textbf{53}, 1818 (1996)]
which includes only material oscillators as fundamental variables. We show in
order to preserve unitarity, causality and time symmetry one must necessarily
include with an equal footing both electromagnetic modes and material
fluctuations on the evolution equations. This becomes particularly relevant for
all nanophotonics and plasmonics problems involving spatially localized
antennas or devices.
