Sharp Superconductor-Insulator Transition in Short Wires

TL;DR

This paper explains the sharp superconductor-insulator transition in short nanowires at a critical resistance close to the quantum resistance, using a self-consistent renormalization group approach that aligns with recent experiments.

Contribution

The authors develop a self-consistent renormalization group method for phase-slip interactions, revealing a sharp transition at the quantum resistance, contrasting with previous smooth transition predictions.

Findings

Transition is sharp at R_c ≈ R_Q.

Quantitative agreement with experimental resistance measurements.

Method applicable to other sine-Gordon related systems.

Abstract

Recent experiments on short MoGe nanowires show a sharp superconductor-insulator transition tuned by the normal state resistance of the wire, with a critical resistance of $R_c\approx R_Q= h/(4e^2)$. These results are at odds with a broad range of theoretical work on Josephson-like systems that predicts a smooth transition, tuned by the value of the resistance that shunts the junction. We develop a self-consistent renormalization group treatment of interacting phase-slips and their dual counterparts, correlated cooper pair tunneling, beyond the dilute approximation. This analysis leads to a very sharp transition with a critical resistance of $R_Q$. The addition of the quasi-particles' resistance at finite temperature leads to a quantitative agreement with the experimental results. This self-consistent renormalization group method should also be applicable to other physical systems that can be mapped onto similar sine-Gordon models, in the previously inaccessible intermediate-coupling regime.