发表机构
ICFO—Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology; ICREA—Institució Catalana de Recerca i Estudis Avançats（光子科学研究所，巴塞罗那科学技术研究院; 加泰罗尼亚高级研究学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对SERF磁力计标量减速模型在极化变化时失效的问题，提出含纵向与横向减速因子的动态布洛赫方程，降低磁场估计偏差并保留模型简洁性。
AI 中文摘要
无自旋交换弛豫（SERF）磁力计的约化布洛赫模型通常使用单一核减速因子来描述耦合的电子-核自旋动力学。我们证明，当极化幅度发生显著变化时，这种标量描述变得不准确。我们推导了一个有效的布洛赫方程，其中包含分别控制极化幅度和方向变化的纵向与横向减速因子，$q_\parallel(P)$ 和 $q_\perp(P)$。对于在代表性SERF条件下经历自由感应衰减（FID）的$^{87}\mathrm{Rb}$，与主方程模拟的比较表明，动态标量模型在高初始极化下产生高达$4.2\\%$的磁场估计偏差，而将减速因子固定为参考值则使误差增加到$10.1\\%$。降低极化会抑制这种偏差，但也会减少FID信号中所包含的磁场信息。我们进一步表明，各向异性响应会修改非共线光泵浦，并在周期性驱动下为谐波响应引入额外的非线性贡献。所得模型保留了三分量布洛赫描述的简洁性，同时提高了瞬态和驱动SERF磁力测量的定量精度。
英文摘要
Reduced Bloch models of spin-exchange-relaxation-free (SERF) magnetometers commonly describe the coupled electron--nuclear spin dynamics using a single nuclear slowing-down factor. We show that this scalar description becomes inaccurate when the polarization magnitude changes appreciably. We derive an effective Bloch equation with separate longitudinal and transverse slowing-down factors, $q_\parallel(P)$ and $q_\perp(P)$, governing changes in polarization magnitude and direction. For $^{87}\mathrm{Rb}$ under representative SERF conditions and undergoing free-induction decay (FID), comparison with master-equation simulations shows that the dynamic scalar model produces a magnetic-field estimation bias of up to $4.2\%$ at high initial polarization, while fixing the slowing-down factor at a reference value increases the error to $10.1\%$. Lowering the polarization suppresses this bias but also reduces the magnetic-field information contained in the FID signal. We further show that the anisotropic response modifies noncollinear optical pumping and introduces an additional nonlinear contribution to the harmonic response under periodic driving. The resulting model retains the simplicity of a three-component Bloch description while improving the quantitative accuracy of transient and driven SERF magnetometry.
