An anomalous proximity effect was observed in coplanar Nb-BiSb-Nb junctions. The effect consists of a considerable increase of the critical current with an increase in the distance between the superconducting electrodes. The effect is explained by the quantum character of Cooper pair transport through the normal region. Some advantages of the application of such junctions are discussed.

• Received 20 November 1995

DOI:https://doi.org/10.1103/PhysRevLett.77.3029