We present a Josephson junction based on a Ge-Si core-shell nanowire with transparent superconducting Al contacts, a building block which could be of considerable interest for investigating Majorana bound states, superconducting qubits and Andreev (spin) qubits. We demonstrate the dc Josephson effect in the form of a finite supercurrent through the junction, and establish the ac Josephson effect by showing up to 23 Shapiro steps. We observe multiple Andreev reflections up to the sixth order, indicating that charges can scatter elastically many times inside our junction, and that our interfaces between superconductor and semiconductor are transparent and have low disorder.
@article{arxiv.1908.07579,
title = {Multiple Andreev reflections and Shapiro steps in a Ge-Si nanowire Josephson junction},
author = {Joost Ridderbos and Matthias Brauns and Ang Li and Erik P. A. M. Bakkers and Alexander Brinkman and Wilfred G. van der Wiel and Floris A. Zwanenburg},
journal= {arXiv preprint arXiv:1908.07579},
year = {2019}
}