Nanoscale Stray Fields from Micromagnets for Optimal Spin Qubit Architecture.
basic_science · Level V
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- Record sourced from PubMed, PMID 42503876.
- Also identified by DOI 10.1021/acs.nanolett.6c01469.
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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 |<i>g</i><sub>s</sub>/<i>g</i><sub>c</sub> | ≈ 0.5, where <i>g</i><sub>c</sub> denotes the charge-photon coupling strength of the underlying charge qubit, highlighting the potential for high-fidelity operations in circuit QED architectures.