Universal distribution of transparencies in highly conductive Nb/AlOx/Nb junctions

We report the observation of the universal distribution of transparencies, predicted by Schep and Bauer [Phys. Rev. Left. 783 3015 (1997)] for dirty sharp interfaces, in uniform Nb/AlOx/Nb junctions with high specific conductance (10(8) ohm(-1) cm(-2)). Experiments used the BCS density of states in superconducting niobium for transparency distribution probing. Experimental results for both the de I-V curves at magnetic-field-suppressed supercurrent and the Josephson critical current in zero magnetic field coincide remarkably well with calculations based on the multimode theory of multiple Andreev reflections and the Schep-Bauer distribution.