Superconductor-to-normal transition in finite nanowires

TL;DR

This paper investigates the superconductor-to-normal transition in finite nanowires, revealing how quantum fluctuations, dissipation, and wire length influence the transition, with implications for understanding superconductivity in nanoscale systems.

Contribution

It introduces a phenomenological model showing phase-slip dipoles cause decoupling of superconductor and normal fluids, affecting transition behavior based on wire length and total resistance.

Findings

Long wires undergo a superconductor-metal transition influenced by local properties.

Short wires transition when total resistance reaches the quantum resistance R_Q.

Phase-slip dipoles lead to decoupling of superfluid and normal components in the wire.

Abstract

In this paper we discuss the interplay of quantum fluctuations and dissipation in uniform superconducting nanowires. We consider a phenomenological model with superconducting and normal components, and a finite equilibration rate between these two-fluids. We find that phase-slip dipoles proliferate in the wire, and decouple the two-fluids within its bulk. This implies that the the normal fluid only couples to the superconductor fluid through the leads at the edges of the wire, and the {\it local} dissipation is unimportant. Therefore, while long wires have a superconductor-metal transition tuned by local properties of the superconducting fluid, short wires have a transition when the {\it total} resistance is $R_{total}=R_Q=h/4e^2$.