Year: 2026
Type: article
Abstract: On-chip micromagnets generate local magnetic-field asymmetries, enabling electrical control of spin qubits via electric dipole spin resonance and their integration into circuit quantum electrodynamics (QED) architectures. Accurate prediction of spin-qubit performance requires modeling micromagnet stray fields beyond the saturated-magnet approximation, accounting for nonuniform magnetization. Here, we combine thin-film characterization of Co, Co/Ta multilayers, and CoFe films with nanoscale stray-field measurements using NV-center magnetometry in the unsaturated regime to establish a reliable micromagnetic simulation framework. We show that CoFe micromagnets generate antisymmetric fields in double quantum-dot geometries exceeding ±100 mT, owing to their high saturation magnetization and favorable magnetocrystalline anisotropy. For spin qubits coupled to microwave resonators, the predicted spin-photon coupling reaches |gs/gc | ≈ 0.5, where gc denotes the charge-photon coupling strength of the underlying charge qubit, highlighting the potential for high-fidelity operations in circuit QED architectures.
Source: Nano Letters
Authors: S. Lopes, Q. Schaeverbeke, M. M. Desjardins, D. Lacour, M. Hehn, F. Montaigne
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funder: Agence Nationale de la Recherche
OpenAlex ID: W7171451445