Andreev Modes from Phase Winding in a Full-Shell Nanowire-Based Transmon

We investigate transmon qubits made from semiconductor nanowires with a fully surrounding superconducting shell. In the regime of reentrant superconductivity associated destructive Little-Parks effect, numerous coherent transitions are observed in first lobe, where shell carries 2{\pi} winding phase, and absent zeroth lobe. As junction density was increased by gate voltage, qubit coherence suppressed then lost These observations numerical simulations highlight role winding-induced Andreev states junction.