用于优化自旋量子比特架构的微磁体的纳米级杂散场
Nanoscale stray fields from micromagnets for optimal spin qubit architecture
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中文总结 AI 辅助
研究微磁体纳米级杂散场对自旋量子比特性能的影响，结合薄膜表征与杂散场测量建立模拟框架，发现钴铁微磁体产生强反对称场，预测自旋-光子耦合效果好，为电路QED架构高保真操作提供潜力。
中文摘要 AI 辅助
片上微磁体产生局部磁场不对称性，可通过电偶极子自旋共振对自旋量子比特进行电控制，并将其集成到电路量子电动力学（QED）架构中。准确预测自旋量子比特性能需要对微磁体杂散场进行建模，超越饱和磁体近似，考虑非均匀磁化。本文结合钴、钴/钽多层膜和钴铁薄膜的薄膜表征与非饱和状态下使用NV中心磁力测量的纳米级杂散场测量，建立可靠的微磁模拟框架。结果表明，钴铁微磁体在双量子点几何结构中产生超过±100mT的反对称场，对于与微波谐振器耦合的自旋量子比特，预测的自旋-光子耦合达到|gs/gc|≈0.5，凸显了电路QED架构中高保真操作的潜力。
英文摘要
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 +/- 100mT, owing to their high saturation magnetization and favorable magnetocrystalline anisotropy. For spin qubits coupled to microwave resonators, the predicted spin-photon coupling reaches $\left| g_s/g_c \right| \approx 0.5$, where $g_c$ denotes the charge-photon coupling strength of the underlying charge qubit, highlighting the potential for high-fidelity operations in circuit QED architectures.
