Giant Josephson current through a single bound state in a superconducting tunnel junction

TL;DR

This paper investigates the microscopic structure of Josephson current in a single-mode tunnel junction, revealing how resonance coupling significantly enhances the current carried by a single Andreev bound state.

Contribution

It introduces a detailed analysis of the bound state current enhancement due to resonance coupling in superconducting tunnel junctions.

Findings

Resonance coupling causes tremendous enhancement of bound state current.

Each Andreev bound state carries a current proportional to normal electron transmission amplitude.

Potential for experimental observation of single bound state current is discussed.

Abstract

We study the microscopic structure of the Josephson current in a single-mode tunnel junction with a wide quasiclassical tunnel barrier. In such a junction each Andreev bound state carries a current of magnitude proportional to the {\em amplitude} of the normal electron transmission through the junction. Tremendous enhancement of the bound state current is caused by the resonance coupling of superconducting bound states at both superconductor-insulator interfaces of the junction. The possibility of experimental observation of the single bound state current is discussed.