  Superconductors with p+ip pairing symmetry are characterized by chiral edge
states, but these are difficult to detect in equilibrium since the resulting
magnetic field is screened by the Meissner effect. Nonequilibrium detection is
hindered by the fact that the edge excitations are unpaired Majorana fermions,
which cannot transport charge near the Fermi level. Here we show that the
boundary between p_x+ip_y and p_x-ip_y domains forms a one-way channel for
electrical charge. We derive a product rule for the domain wall conductance,
which allows to cancel the effect of a tunnel barrier between metal electrodes
and superconductor and provides a unique signature of topological
superconductors in the chiral p-wave symmetry class.
