  A new technique is described by which light-induced gauge potentials allow
systems of ultra-cold neutral atoms to behave like charged particles in a
magnetic field. Here, atoms move in a uniform laser field with a spatially
varying Zeeman shift and experience an effective magnetic field. This technique
is applicable for atoms with two or more internal ground states. Finally, an
explicit model of the system using a single-mode 2D Gross-Pitaevskii equation
yields the expected vortex lattice.
