Condensate entanglement and multigap superconductivity in nanoscale superconductors

TL;DR

This paper investigates how quantum size effects induce multigap superconductivity and condensate entanglement in nanoscale superconductors, revealing universal features of confined superconducting systems.

Contribution

It introduces a Green functions approach to demonstrate the critical role of condensate entanglement and multigap behavior in nanoscale superconductors, highlighting their universality.

Findings

Superconductivity arises from multimodal entanglement of subcondensates.

Multigap superconductivity significantly affects critical parameters.

Condensate entanglement is essential for robust superconductivity in nanostructures.

Abstract

A Green functions approach is used to study superconductivity in nanofilms and nanowires. We show that the superconducting condensate results from the multimodal entanglement, or internal Josephson coupling, of the subcondensates associated with the manifold of Fermi surface subparts resulting from size-quantisation. This entanglement is of critical importance in these systems, since without it superconductivity would be extremely weak, if not completely negligible. Further, the multimodal character of the condensate generally results in multigap superconductivity, with great quantitative consequence for the value of the critical parameters. Our approach suggests that these are universal characteristics of confined superconductors.