Supercurrent and noise in point contact between two different superconductors

TL;DR

This paper investigates how supercurrent and noise behave in a quantum point contact between two different superconductors, revealing unique phenomena when their gap magnitudes differ, including the absence of Andreev bound states for certain conditions.

Contribution

It demonstrates that in hetero-gap superconductor contacts, Andreev bound states can be absent, leading to different transport and noise characteristics compared to equal-gap systems.

Findings

Andreev bound states may not exist for certain phase differences and gap ratios.

Continuum states can dominate transport in hetero-gap contacts.

Supercurrent noise behavior differs qualitatively from equal-gap cases.

Abstract

We show that, for a quantum point contact between two superconductors of different gap magnitudes, Andreev bound states do not exist for certain phase differences and gap ratios. Continuum states may dominate the transport, and the supercurrent noise is qualitatively different from the case of equal gaps.