Supercurrent parity meter in a nanowire Cooper pair transistor

Ji Yin Wang, Constantin Schrade, Vukan Levajac, David van Driel, Kongyi Li, Ghada Badawy, Joon Sue Lee, Leo P. Kouwenhoven, Jie Shen*, More Authors

*Corresponding author for this work

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We study a Cooper pair transistor realized by two Josephson weak links that enclose a superconducting island in an InSb-Al hybrid nanowire. When the nanowire is subject to a magnetic field, isolated subgap levels arise in the superconducting island and, because of the Coulomb blockade, mediate a supercurrent by coherent cotunneling of Cooper pairs. We show that the supercurrent resulting from such cotunneling events exhibits, for low to moderate magnetic fields, a phase offset that discriminates even and odd charge ground states on the superconducting island. Notably, this phase offset persists when a subgap state approaches zero energy and, based on theoretical considerations, permits parity measurements of subgap states by supercurrent interferometry. Such supercurrent parity measurements could, in a series of experiments, provide an alternative approach for manipulating and protecting quantum information stored in the isolated subgap levels of superconducting islands.

Original languageEnglish
Article numberabm9896
Number of pages5
JournalScience Advances
Issue number16
Publication statusPublished - 2022


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