Fermion parity of an Andreev molecule probed by nonlocal Josephson effect

Abstract:Fermion parity is a fundamental property of superconducting many-body states. Here, we show that the global fermion parity of a delocalized superconducting state can be detected locally by exploiting the nonlocal Josephson effect. Using a carbon nanotube-based Andreev molecule formed by two coupled quantum-dot Josephson junctions, we observe a pronounced nonlocal Josephson response and demonstrate the formation of delocalized Andreev molecular states extending across both junctions. We further show that changes in the molecular ground-state parity manifest as characteristic $\pi$-phase shifts in the nonlocal response. Supported by a minimal theoretical model, these results identify global fermion parity as an experimentally accessible degree of freedom in hybrid superconducting circuits that can be readily revealed through the nonlocal Josephson effect.

Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Superconductivity (cond-mat.supr-con); Quantum Physics (quant-ph)

arXiv:2607.15786 [cond-mat.mes-hall]

(or arXiv:2607.15786v1 [cond-mat.mes-hall] for this version)

https://doi.org/10.48550/arXiv.2607.15786 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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