Quantum point contact conductance in NINS junctions

TL;DR

This paper investigates how an insulating barrier near a quantum point contact affects conductance in NINS junctions, revealing that the number and position of resonances depend on the superconductor's pairing symmetry and barrier parameters.

Contribution

It introduces a detailed analysis of bound states and conductance resonances in NINS junctions, highlighting the influence of barrier position and symmetry of the order parameter.

Findings

Resonances in conductance depend on pair potential symmetry.

Number of resonances varies with the symmetry of the superconductor.

Resonance positions are affected by the barrier and distance a.

Abstract

The effect of an insulating barrier located at a distance $a$ from a NS quantum point contact is analyzed in this work. The Bogoliubov de Gennes equations are solved for NINS junctions (S: anysotropic superconductor, I: insulator and N: normal metal), where the NIN region is a quantum wire. For $% a\neq0$, bound 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 $a $. 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.