Quantum point contact conductance in normal-metal/insulator/metal/superconductor junctions -: art. no. 094515

The effect of an insulating barrier located at alpha distance a from a NS quantum point contact is analyzed in this work. The Bogoliubov-de Gennes equations are solved for NINS junctions (S, anisotropic superconductor; I, insulator; and N, normal metal), where the NIN region is a quantum wire. For alpha not equal 0, quasibound states and resonances in the differential conductance are predicted. These resonances depend on the symmetry of the pair potential, the strength of the insulating barrier and alpha. Our results show that in a NINS quantum point contact the number of resonances vary with the symmetry of the order parameter. This is to be contrasted with the results. for the NINS junction, in which only the position of the resonances changes with the symmetry.