Parity-preserving and magnetic field-resilient superconductivity in InSb nanowires with Sn shells.

Improving materials used to make qubits is crucial to further progress in quantum information processing. Of particular interest are semiconductor-superconductor heterostructures that are expected to form the basis of topological quantum computing. We grow semiconductor indium antimonide nanowires that are coated with shells of tin of uniform thickness. No interdiffusion is observed at the interface between Sn and InSb. Tunnel junctions are prepared by in-situ shadowing. Despite the lack of lattice matching between Sn and InSb a 15 nm thick shell of tin is found to induce a hard superconducting gap, with superconductivity persisting in magnetic field up to 4T. A small island of Sn-InSb exhibits the two-electron charging effect. These findings suggest a less restrictive approach to fabricating superconducting and topological quantum circuits.