Current-phase relations of InAs nanowire Josephson junctions: from interacting to multi-mode regimes

Understand

Gate-tunable semiconductor-superconductor nanowires with superconducting leads form exotic Josephson junctions that are a highly desirable platform for two types of qubits: those with topological superconductivity (Majorana qubits) and those based on tunable anharmonicity (gatemon qubits).

• Controlling their behavior, however, requires understanding their electrostatic environment and electronic structure.
• Here we study gated InAs nanowires with epitaxial aluminum shells.
• By measuring current-phase relations (CPR) and comparing them with analytical and numerical calculations, we show that we can tune the number of modes, determine the transparency of each mode, and tune into regimes in which electron-electron interactions are apparent, indicating the presence of a quantum dot.