  We show that $N-1$ degenerate dark states can be generated by coupling
$N$-fold degenerate ground states and a common excited state with $N$ laser
fields. Interferences between light waves with different frequencies can
produce laser fields with time-dependent amplitudes, which can induce not only
U(N) non-Abelian vector fields but also the scalar ones for the adiabatic
motion of atoms in such laser fields. As an example, a time-periodic gauge
potential is produced by applying specific laser fields to a tripod system.
Some features of the Landau levels and the ground-state phase diagram of a
rotating Bose-Einstein condensate for a concrete gauge field are also
discussed.
