Altermon: a magnetic-field-free parity protected qubit based on a narrow altermagnet Josephson junction

Sakineh Vosoughi-nia; Michał P. Nowak

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arXiv · 2510.18145

Altermon: a magnetic-field-free parity protected qubit based on a narrow altermagnet Josephson junction

Sakineh Vosoughi-nia·Michał P. Nowak

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Abstract

Altermagnets provide a new route to engineer superconducting circuits without magnetic fields. We theoretically study the Andreev bound state (ABS) spectrum of a finite-width altrmagnet-based Josephson junction and show how the $d$-wave altermagnetic symmetry and geometric confinement shape its low-energy excitations. We find a clear distinction between the two $d$-wave symmetries: $d_{x^2-y^2}$ order produces spin splitting, whereas $d_{xy}$ order preserves spin degeneracy and exhibits splitting of the ABS spectrum induced by intermode hybridization. Leveraging these novel features, we propose applying a transverse electric field to tune the system and realize a magnetic-field-free, parity-protected superconducting qubit that we call altermon.

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Sakineh Vosoughi-nia, Michał P. Nowak. 2025-10-20. Altermon: a magnetic-field-free parity protected qubit based on a narrow altermagnet Josephson junction. https://arxiv.org/abs/2510.18145

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