Supercurrent transport through 1$e$-periodic full-shell Coulomb islands

TL;DR

This paper experimentally studies supercurrent transport in semiconducting nanowire Coulomb islands with superconducting shells, revealing flux-dependent supercurrent behavior and Coulomb blockade characteristics consistent with zero-energy states.

Contribution

It provides new experimental insights into supercurrent behavior and Coulomb blockade in full-shell nanowire islands, supported by a theoretical model of zero-energy state transport.

Findings

Observation of flux-dependent supercurrent with Little-Parks oscillations

Coulomb blockade with 2e and 1e peak spacings in different lobes

Correlation of Coulomb-peak amplitude evolution with zero-energy states

Abstract

We experimentally investigate supercurrent through Coulomb islands, where island and leads are fabricated from semiconducting nanowires with fully surrounding superconducting shells. Applying flux along the wire yields a series of destructive Little-Parks lobes with reentrant supercurrent. We find Coulomb blockade with 2$e$ peak spacing in the zeroth lobe and 1$e$ average spacing, with regions of significant even-odd modulation, in the first lobe. Evolution of Coulomb-peak amplitude through the first lobe is consistent with a theoretical model of supercurrent carried predominantly by zero-energy states in the leads and the island.