Dissipative Macroscopic Quantum Tunneling in Type-I Superconductors

TL;DR

This paper models the dissipative quantum tunneling of interfaces in type-I superconductors, analyzing the transition from thermal activation to quantum tunneling and proposing experimental observations of quantum depinning.

Contribution

It develops a mathematical model for dissipative quantum escape of interfaces in type-I superconductors, including instanton solutions and crossover temperature calculations.

Findings

Derived effective action for interface tunneling.

Identified crossover temperature between thermal and quantum regimes.

Suggested experimental observation of quantum depinning in lead superconductors.

Abstract

We study macroscopic quantum tunneling of interfaces separating normal and superconducting regions in type-I superconductors. Mathematical model is developed, that describes dissipative quantum escape of a two-dimensional manifold from a planar potential well. It corresponds to, e.g., a current-driven quantum depinning of the interface from a grain boundary or from artificially manufactured pinning layer. Effective action is derived and instantons of the equations of motion are investigated. Crossover between thermal activation and quantum tunneling is studied and the crossover temperature is computed. Our results, together with recent observation of non-thermal low-temperature magnetic relaxation in lead, suggest possibility of a controlled measurement of quantum depinning of the interface in a type-I superconductor.