  A quantum effect characterized by a dependence of the angular frequency
associated with the confinement of a neutral particle to a quantum ring on the
quantum numbers of the system and the Aharonov-Casher geometric phase is
discussed. Then, it is shown that persistent spin currents can arise in a
two-dimensional quantum ring in the presence of a Coulomb-type potential. A
particular contribution to the persistent spin currents arises from the
dependence of the angular frequency on the geometric quantum phase.
