  A dc voltage drop develops along amorphous indium oxide nanowires that are
exposed to an ac bias source. This voltage is anti-symmetric with magnetic
field and is characterized by sample specific quasi-periodic magneto-voltage
oscillations. The voltage magnitude increases with decreasing temperature below
$T_{C}$ but saturates at low T. As the disorder of the sample is decreased, the
dc voltage is suppressed. We suggest that this rectification is a manifestation
of the superconducting ratchet effect in which disorder and geometrical
confinement play the role of asymmetric pinning centers. This effect
demonstrates the importance of inherent inhomogeneity and vortex motion in the
superconductor-insulator transition of disordered superconductors.
