MACROSCOPIC FLUCTUATIONS IN THE BOUNDARY RESISTANCE OF METAL-SUPERCONDUCTOR INTERFACES

We examine the possibility of macroscopic fluctuations in the electric al resistance R of a disordered mesoscopic superconductor. A Perturbat ive argument shows that in the presence of phase fluctuations, quantum interference can cause the Andreev scattering amplitude to vanish, le ading to a 1/R2 tail in the probability distribution for R. Consequent ly no moments exist and the boundary resistance exhibits large fluctua tions. This prediction is confirmed by numerical simulations on superc onducting loops, connected to external reservoirs by point contacts.