Criss-cross Josephson junction devices with InAs nanowires

Devices based on superconductor-semiconductor nanowire junctions are a building block of superconducting qubits and a platform to discover new physics phenomena, such as Majorana Zero Modes. The quality of these hybrid materials is crucial however the standard method of fabricating junctions by etching can easily damage the nanowires. In-situ superconductor evaporation on crossed nanowire networks can also create nanowire junctions, however it requires a well-developed nanowire growth on a patterned substrate. In this work, we develop a new etch-free technique of fabricating Josephson junction devices based on InAs nanowires. We design these devices by placing one nanowire on top of another in a criss-cross fashion on a gate-tunable semiconductor chip. The top nanowire shadows the bottom one during superconductor evaporation/collimated sputtering which results in a sub-100nm width junction on the bottom nanowire. This could in principle create induced hard gap superconductivity in the nanowire junctions. In this talk we will discuss our progress with fabrication, proof of principle quantum transport data and future work on such devices.