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 transition spectrum of the transmon allows us to probe the ground-state parity of the quantum dot as a function of the gate voltages, the external magnetic flux, and the 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-π qubits and Andreev qubits.
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Data processing and plotting underlying the manuscript: Singlet-doublet transitions of a quantum dot Josephson junction revealed in a transmon circuit
Bargerbos, A. (Creator) & Pita-Vidal, M. (Creator), TU Delft - 4TU.ResearchData, 25 May 2022
Raw timetraces underlying the manuscript: Singlet-doublet transitions of a quantum dot Josephson junction detected in a transmon circuit
Bargerbos, A. (Creator), TU Delft - 4TU.ResearchData, 25 May 2022