  By modeling a linear polarizable and magnetizable medium (magneto-dielectric)
with two quantum fields, namely E and M, electromagnetic field is quantized in
such a medium consistently and systematically. A Hamiltonian is proposed from
which, using the Heisenberg equations, Maxwell and constitutive equations of
the medium are obtained. For a homogeneous medium, the equation of motion of
the quantum vector potential, $\vec{A}$, is derived and solved analytically.
Two coupling functions which describe the electromagnetic properties of the
medium are introduced. Four examples are considered showing the features and
the applicability of the model to both absorptive and nonabsorptive
magneto-dielectrics.
