Destructive Little-Parks Effect in a Full-Shell Nanowire-based Transmon

Understand

A semiconductor transmon with an epitaxial Al shell fully surrounding an InAs nanowire core is investigated in the low $E_J/E_C$ regime.

• Little-Parks oscillations as a function of flux along the hybrid wire axis are destructive, creating lobes of reentrant superconductivity separated by a metallic state at a half-quantum of applied flux.
• In the first lobe, phase winding around the shell can induce topological superconductivity in the core.
• Coherent qubit operation is observed in both the zeroth and first lobes.