Hard-gap spectroscopy in a self-defined mesoscopic InAs/Al nanowire Josephson junction

Abstract

Superconductor/semiconductor-nanowire hybrid structures can serve as versatile building blocks to realize Majorana circuits or superconducting qubits based on quantized levels such as Andreev qubits. For all these applications it is essential that the superconductor-semiconductor interface is as clean as possible. Furthermore, the shape and dimensions of the superconducting electrodes needs to be precisely controlled. We fabricated self-defined InAs/Al core/shell nanowire junctions by a fully in-situ approach, which meet all these criteria. Transmission electron microscopy measurements confirm the sharp and clean interface between the nanowire and the in-situ deposited Al electrodes which were formed by means of shadow evaporation. Furthermore, we report on tunnel spectroscopy, gate and magnetic field-dependent transport measurements. The achievable short junction lengths,the observed hard-gap and the magnetic field robustness make this new hybrid structure very attractive for applications which rely on a precise control of the number of sub-gap states, like Andreev qubits or topological systems.

arXiv comment9 pages, 6 figures. Inclusion of additional TEM and EDX data

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Cited by in corpus (6)

• Epitaxial Superconductor-Semiconductor Two-Dimensional Systems for Superconducting Quantum Circuits
• Progress in superconductor-semiconductor topological Josephson junctions
• Fully in-situ InAs nanowire Josephson junctions by selective-area growth and shadow evaporation
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• Josephson effect and critical currents in trivial and topological full-shell hybrid nanowires