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arXiv · 2208.09314

Spectroscopy of spin-split Andreev levels in a quantum dot with superconducting leads

Arno Bargerbos·Marta Pita-Vidal·Rok Žitko·Lukas J. Splitthoff·Lukas Grünhaupt·Jaap J. Wesdorp·Yu Liu·Leo P. Kouwenhoven·Ramón Aguado·Christian Kraglund Andersen·Angela Kou·Bernard van Heck
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Abstract

We use a hybrid superconductor-semiconductor transmon device to perform spectroscopy of a quantum dot Josephson junction tuned to be in a spin-1/2 ground state with an unpaired quasiparticle. Due to spin-orbit coupling, we resolve two flux-sensitive branches in the transmon spectrum, depending on the spin of the quasi-particle. A finite magnetic field shifts the two branches in energy, favoring one spin state and resulting in the anomalous Josephson effect. We demonstrate the excitation of the direct spin-flip transition using all-electrical control. Manipulation and control of the spin-flip transition enable the future implementation of charging energy protected Andreev spin qubits.

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Arno Bargerbos, Marta Pita-Vidal, Rok Žitko, Lukas J. Splitthoff, Lukas Grünhaupt, Jaap J. Wesdorp, Yu Liu, Leo P. Kouwenhoven, Ramón Aguado, Christian Kraglund Andersen, Angela Kou, Bernard van Heck. 2022-08-19. Spectroscopy of spin-split Andreev levels in a quantum dot with superconducting leads. https://doi.org/10.1103/physrevlett.131.097001

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