Weak links in proximity superconducting two dimensional electron systems

We report a giant inverse proximity effect that arises in the low-dimensional devices and is crucially different from proximity in the standard superconductor-normal-superconductor (S/N/S) junctions. The normal conductors induce a giant back-action on the proximity superconducting regions even when the dimensions of the normal parts are smaller than the proximity coherence length. This essentially suppresses the superconducting characteristics of the entire system, including the critical current, well below those for the usual S/N/S structures.