Singlet-doublet transitions of a quantum dot Josephson junction detected in a transmon circuit

Abstract

We realize a hybrid superconductor-semiconductor transmon device in which the Josephson effect is controlled by a gate-defined quantum dot in an InAs/Al nanowire. Microwave spectroscopy of the transmon's transition spectrum allows us to probe the ground state parity of the quantum dot as a function of gate voltages, external magnetic flux, and magnetic field applied parallel to the nanowire. The measured parity phase diagram is in agreement with that predicted by a single-impurity Anderson model with superconducting leads. Through continuous time monitoring of the circuit we furthermore resolve the quasiparticle dynamics of the quantum dot Josephson junction across the phase boundaries. Our results can facilitate the realization of semiconductor-based $0-\pi$ qubits and Andreev qubits.

Main text has 14 pages, 7 figures. Supplement has 21 pages, 21 figures

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Cited by in corpus (8)

• Direct manipulation of a superconducting spin qubit strongly coupled to a transmon qubit
• Spectroscopy of spin-split Andreev levels in a quantum dot with superconducting leads
• Supercurrent reversal in ferromagnetic hybrid nanowire Josephson junctions
• Microwave spectroscopy of interacting Andreev spins
• Quantum phase slips in a resonant Josephson junction
• Impurity Knight shift in quantum dot Josephson junctions
• SWAP gate between a Majorana qubit and a parity-protected superconducting qubit
• Microwave susceptibility observation of interacting many-body Andreev states