Interplay of the inverse proximity effect and magnetic field in out-of-equilibrium single-electron devices

TL;DR

This paper investigates how magnetic fields influence non-equilibrium quasiparticle distributions in single-electron hybrid devices, revealing effects on superconducting gaps and device performance with implications for quantum technologies.

Contribution

It provides experimental evidence and theoretical analysis of the interplay between inverse proximity effect and magnetic field in superconducting devices, highlighting new mechanisms for quasiparticle control.

Findings

Magnetic field suppresses the superconducting gap near junctions.

Magnetic field creates quasiparticle traps via vortices or reduced gap regions.

Enhanced superconducting gap and improved device characteristics observed with magnetic field.

Abstract

The magnetic field is shown to affect significantly non-equilibrium quasiparticle (QP) distributions under conditions of inverse proximity effect on the remarkable example of a single-electron hybrid turnstile. This effect suppresses the gap in the superconducting leads in the vicinity of turnstile junctions with a Coulomb blockaded island, thus, trapping hot QPs in this region. Applied magnetic field creates additional QP traps in the form of vortices or regions with reduced superconducting gap in the leads resulting in release of QPs away from junctions. We present clear experimental evidence of such interplay of the inverse proximity effect and a magnetic field revealing itself in the superconducting gap enhancement in a magnetic field as well as in significant improvement of the turnstile characteristics. The observed interplay of the inverse proximity effect and external magnetic field, and its theoretical explanation in the context of QP overheating are important for various superconducting and hybrid nanoelectronic devices, which find applications in quantum computation, photon detection and quantum metrology.