Josephson effect in a few-hole quantum dot

TL;DR

This paper demonstrates a Ge-Si nanowire Josephson transistor that reveals two distinct supercurrent regimes, advancing the understanding of hybrid superconductor-semiconductor systems and potential Majorana fermion applications.

Contribution

It introduces a Ge-Si nanowire device capable of accessing both multi-subband and few-hole quantum dot regimes within a single platform.

Findings

High transparency supercurrent in accumulation mode

Supercurrent carried by single-particle levels near depletion

Establishment of Ge-Si nanowires as a platform for Majorana physics

Abstract

We use a Ge-Si core-shell nanowire to realise a Josephson field-effect transistor with highly transparent contacts to superconducting leads. By changing the electric field we gain access to two distinct regimes not combined before in a single device: In the accumulation mode the device is highly transparent and the supercurrent is carried by multiple subbands, while near depletion supercurrent is carried by single-particle levels of a strongly coupled quantum dot operating in the few-hole regime. These results establish Ge-Si nanowires as an important platform for hybrid superconductor-semiconductor physics and Majorana fermions.