Supercurrent parity-meter in a nanowire Cooper-pair transistor

• Published in: arXiv.org
• Main Authors: Ji-Yin, Wang, Schrade, Constantin, Levajac, Vukan, David van Driel, Li, Kongyi, Gazibegovic, Sasa, Badawy, Ghada, Roy L M Op het Veld, Lee, Joon Sue, Pendharkar, Mihir, Dempsey, Connor P, Palmstrøm, Chris J, Erik P A M Bakkers, Fu, Liang, Kouwenhoven, Leo P, Shen, Jie
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 18.07.2021
• Subjects: Cooper pairs; Magnetic fields; Nanowires; Parity; Physics - Applied Physics; Physics - Mesoscale and Nanoscale Physics; Physics - Quantum Physics; Physics - Superconductivity; Quantum phenomena; Semiconductor devices; Superconductivity; Transistors
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2107.08466

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, due to the Coulomb blockade,mediate a supercurrent by coherent co-tunneling of Cooper pairs. We show that the supercurrent resulting from such co-tunneling 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 new series of experiments, provide an alternative approach for manipulating and protecting quantum information stored in the isolated subgap levels of superconducting islands.