Semiconductor nanowires coupled to a superconductor provide a powerful testbed for quantum device physics such as Majorana zero modes and gate-tunable hybrid qubits. The performance of these quantum devices heavily relies on the quality of the induced superconducting gap. A hard gap, evident as vanishing subgap conductance in tunneling spectroscopy, is both necessary and desired. Previously, a hard gap has been achieved and extensively studied in III-V semiconductor nanowires (InAs and InSb). In this study, we present the observation of a hard superconducting gap in PbTe nanowires coupled to a superconductor Pb. The gap size (Δ) is ∼ 1 meV (maximally 1.3 meV in one device). Additionally, subgap Andreev bound states can also be created and controlled through gate tuning. Tuning a device into the open regime can reveal Andreev enhancement of the subgap conductance, suggesting a remarkable transparent superconductor-semiconductor interface, with a transparency of ∼ 0.96. These results pave the way for diverse superconducting quantum devices based on PbTe nanowires.
@article{arxiv.2309.01355,
title = {Hard superconducting gap in PbTe nanowires},
author = {Yichun Gao and Wenyu Song and Shuai Yang and Zehao Yu and Ruidong Li and Wentao Miao and Yuhao Wang and Fangting Chen and Zuhan Geng and Lining Yang and Zezhou Xia and Xiao Feng and Yunyi Zang and Lin Li and Runan Shang and Qi-Kun Xue and Ke He and Hao Zhang},
journal= {arXiv preprint arXiv:2309.01355},
year = {2024}
}