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arXiv · 2607.15786

Fermion parity of an Andreev molecule probed by nonlocal Josephson effect

S. Annabi·H. Riechert·K. Watanabe·T. Taniguchi·J. Griesmar·E. Arrighi·L. Bretheau·J. -D. Pillet
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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.

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S. Annabi, H. Riechert, K. Watanabe, T. Taniguchi, J. Griesmar, E. Arrighi, L. Bretheau, J. -D. Pillet. 2026-07-17. Fermion parity of an Andreev molecule probed by nonlocal Josephson effect. https://arxiv.org/abs/2607.15786

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