Tunneling in two-channel Kondo superconducting junctions

Charge transport in the short weak links (K) between two superconductors (S) or between a normal metal (N) and a superconductor is considered. The electron scattering in the weak link is accomplished by two-level systems acting as two-channel Kondo impurities. The impact of this interaction on conductance in the NKS tunnel structure as well as on the Josephson current in SKS junctions is analyzed. It is shown that the conductance of NKS systems as a function of temperature T has a dip at low temperatures, an effect similar to that in NKN junctions. The critical Josephson current: of SKS junctions shows a temperature dependence which deviates from such a dependence of ballistic superconducting contacts.