近日，北京航空航天大学的邹升及其研究团队取得一项新进展。经过不懈努力，他们对基于原子对齐态的强纵向射频磁场存在下的高阶磁共振进行了研究。相关研究成果已于2024年4月26日在国际知名学术期刊《物理评论A》上发表。

该团队研究了在静态横向磁场存在下沿z方向以拉莫尔频率共振的纵向射频(rf)磁场。⁸⁵Rb中的光-射频双共振通过⁸⁵Rb原子的进动频率表征了外磁场的强度。测量是在具有自旋对准配置的石蜡涂层⁸⁵Rb单元中进行的。研究人员在拉莫尔频率的次谐波处观察到一个有趣的磁共振峰，其伴随着共振附近非线性效应的出现。

当拉莫尔频率达到零时，射频磁场诱导的旋光信号呈现出射频频率高次谐波的叠加效应。借助简化的密度矩阵形式和微扰处理，研究人员推导出的旋光解析表达式与实验结果高度吻合。这些重要发现不仅有助于研究人员更深入地理解，塞曼亚能级之间布居和相干性的动态变化，还有望推动对齐磁力学领域的知识进步。

附：英文原文

Title: High-order magnetic resonance in the presence of strong longitudinal radio-frequency magnetic field based on atomic alignment states

Author: Tao Shi, Ge Jin, Sheng Zou

Issue&Volume: 2024/04/26

Abstract: A longitudinal radio-frequency (rf) magnetic field resonating at the Larmor frequency along the z direction in the presence of a static transverse magnetic field is investigated. Optical-radio-frequency double resonance in ⁸⁵Rb characterizes the strength of an external magnetic field through the precession frequency of ⁸⁵Rb atoms. The measurements are carried out in a paraffin-coated ⁸⁵Rb cell with a spin alignment configuration. An intriguing discovery of magnetic resonance peaks is observed at subharmonics of the Larmor frequency, accompanied by the emergence of nonlinear effects in the vicinity of the resonance. Notably, when the Larmor frequency reaches zero, the optical rotation signals induced by the rf magnetic field demonstrate a superposition of high-order harmonics of the rf frequency. Based on the simplified density matrix formalism and perturbation treatment, analytical expressions for the optical rotation are consistent with experimental outcomes. These findings hold the potential of extending our understanding on unveiling the dynamics of population and coherence among Zeeman sublevels, thereby advancing our knowledge in the field of alignment magnetometry.

DOI: 10.1103/PhysRevA.109.043117

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.043117