  The Schrodinger motion of a charged quantum particle in an electromagnetic
potential can be simulated by the paraxial dynamics of photons propagating
through a spatially inhomogeneous medium. The inhomogeneity induces geometric
effects that generate an artificial vector potential to which signal photons
are coupled. This phenomenon can be implemented with slow light propagating
through an a gas of double-Lambda atoms in an electromagnetically-induced
transparency setting with spatially varied control fields. It can lead to a
reduced dispersion of signal photons and a topological phase shift of
Aharonov-Bohm type.
