发表机构
Institute of Electronic Structure and Laser, Foundation for Research and Technology; Department of Physics, Princeton University（电子结构与激光研究所，研究与技术基金会; 普林斯顿大学物理系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文通过微扰理论推导出碱金属蒸气中纵向与横向自旋动力学不同的极化相关核减速因子，并给出有限磁场下残余自旋交换弛豫的闭式表达式，细化了SERF regime下的有效Bloch描述，对原子磁力计和共磁力计有直接应用价值。
AI 中文摘要
核减速因子描述了在自旋交换弛豫自由（SERF） regime 下碱金属自旋动力学的有效 Bloch 描述中电子与原子核之间的角动量共享。对于共线光泵浦和磁场，我们发现纵向和横向自旋动力学由不同的极化相关减速因子表征。横向动力学由常规因子 $q(p)$ 控制，其中 $p$ 是电子自旋极化，而纵向弛豫由 $q(p)+p\,dq(p)/dp$ 控制。这两个因子在零极化时一致，但在高极化时差异显著，此时单因子描述将根据核自旋的不同，高估从纵向瞬态推断的底层泵浦和弛豫速率达两到四倍。我们进一步推导了在任意极化下有效的闭式表达式，用于描述沿泵浦轴的有限磁场下横向自旋分量的残余自旋交换弛豫。该贡献与磁场的平方成正比，在 SERF regime 内的磁场下可与零场线宽相当。这些结果通过对稳态附近线性化的密度矩阵动力学进行微扰理论获得，并通过微观密度矩阵方程的数值解得到验证。这些发现细化了碱金属自旋动力学的有效 Bloch 描述，并直接适用于原子磁力计和碱金属-惰性气体共磁力计，包括用于超越标准模型物理的精密搜索的那些。
英文摘要
Nuclear slowing-down factors account for the sharing of angular momentum between the electron and the nucleus in the effective Bloch description of alkali-metal spin dynamics in the spin-exchange-relaxation-free (SERF) regime. For collinear optical pumping and magnetic field, we find that longitudinal and transverse spin dynamics are characterized by different polarization-dependent slowing-down factors. Transverse dynamics are governed by the conventional factor $q(p)$, with $p$ the electron spin polarization, whereas longitudinal relaxation is governed by $q(p)+p\,dq(p)/dp$. The two factors coincide at zero polarization but differ substantially at high polarization, where the single-factor description overestimates the underlying pumping and relaxation rates inferred from longitudinal transients by factors approaching two to four, depending on the nuclear spin. We further derive closed-form expressions, valid at arbitrary polarization, for the residual spin-exchange relaxation of the transverse spin components at finite magnetic field along the pumping axis. This contribution is quadratic in the magnetic field and can become comparable to the zero-field linewidth at fields well within the SERF regime. The results are obtained by perturbation theory on the density-matrix dynamics linearized around the stationary state and are verified by numerical solutions of the microscopic density-matrix equation. These findings refine the effective Bloch description of alkali-metal spin dynamics and are directly relevant to atomic magnetometers and alkali-metal--noble-gas comagnetometers, including those used in precision searches for physics beyond the Standard Model.
