Absence of Josephson coupling between certain superconductors

TL;DR

This paper argues that Josephson tunneling only occurs between superconductors with charge carriers of the same sign, implying that observing such tunneling confirms similar charge carrier types and supports the hole superconductivity theory.

Contribution

It introduces the idea that Josephson tunneling absence indicates opposite charge carrier signs, offering a new perspective on superconductor pairing mechanisms.

Findings

Josephson tunneling does not occur between superconductors with opposite charge carriers.

Observation of Josephson tunneling implies same sign of charge carriers.

Supports the hole superconductivity theory.

Abstract

It is generally believed that superconductivity can occur in materials irrespective of whether the charge carriers in the material are electrons or holes. Here we point out that Josephson tunneling would not occur between superconductors with charge carriers of opposite sign. Consequently, observation of Josephson tunneling between two superconductors implies that their charge carriers have the same sign. We propose that this has profound implications for the understanding of superconductivity and in particular is consistent with the theory of hole superconductivity.