Transport in mesoscopic proximity systems: A quasiclassical perspective

We discuss the impact of the proximity effect (PE) on the transport propert ies of mesoscopic superconducting-normal structures using the quasiclassica l Green's function technique. We discuss the properties of dissipationless supercurrents in proximity systems as well as the enhanced diffusion conduc tivity in nonequilibrium, which shows a nonmontonic, "reentrant" temperatur e-dependence. Both contributions can be can be controlled by an external ph ase. In nonequilibrium situations, SNS junctions exhibit novel phenomena li ke supercurrent reversal or a nonequilibrium-enhanced critical current. The connection to recent experiments is discussed.