Quantum Tunneling of Normal-Superconducting Interfaces in a Type-I Superconductor

TL;DR

This paper presents evidence of quantum tunneling in the intermediate state of a type-I superconductor, linking magnetic relaxation to quantum interface tunneling and estimating relevant parameters.

Contribution

It provides experimental evidence and theoretical analysis of quantum tunneling of normal-superconducting interfaces in a type-I superconductor, including barrier estimation and crossover temperature.

Findings

Observation of non-thermal magnetic relaxation.

Identification of quantum tunneling as the relaxation mechanism.

Estimation of tunneling barrier parameters.

Abstract

Evidence of a non-thermal magnetic relaxation in the intermediate state of a type-I superconducor is presented. It is attributed to quantum tunneling of interfaces separating normal and superconducting regions. Tunneling barriers are estimated and temperature of the crossover from thermal to quantum regime is obtained from Caldeira-Leggett theory. Comparison between theory and experiment points to tunneling of interface segments of size comparable to the coherence length, by steps of order one nanometer.