高灵敏度“临界SERF态”非屏蔽原子磁传感机制研究

Spin-exchange-relaxation-free (SERF) effect can be utilized to attain the weakly magnetic information in the fields like deep resource electromagnetic detection and biomedical magnetic resonance imaging due to the elimination of the broadening contribution of spin exchange collision to depress the quantum noise. Whereas the effect needs to meet the extremely weakly magnetic field conditions, which restricts the application of magnetic sensors into the outdoor unshielded environment. This project proposes the “Near SERF State” regime atomic magnetic.sensing principle which can achieve precise three-axis vectorial magnetic measurements under unshielded condition. It mainly studies alkali atomic “Near SERF” regime forming process, analyses effects the fundamental factors have on atomic spin including polarization, temperature and magnetic field and has research about the relationship between Larmor precession frequency and linewidth of magnetic-resonance yielding a fast and precise determination to identify the working state of alkali atoms. It also studies the mutual interaction on “Near SERF” regime to establish the optimal control plan. The zero-magnetic-signal-tracking technology is utilized to realize the optimization of atomic “Near SERF” State under unshielded condition. It not only can ease the rigor conditions but also can endure the magnetic sensor achieve superior sensitivity to fT/Hz1/2 compared with the one in SERF regime, which can be applied in weakly magnetic field detection in outdoor intricate circumstance to resolve contradiction between the rigor conditions and environmental adaption.

原子无自旋交换弛豫（SERF）效应抑制因自旋交换碰撞引起的量子噪声，可应用于深地资源电磁探测、生物医学磁图成像等领域获取微弱磁场信息。但此效应需满足极弱磁场严苛条件，使传感器无法在野外非屏蔽条件下工作。本项目提出一种“临界SERF态”原子磁传感原理，能够在非屏蔽条件下实现三轴矢量高灵敏度磁测量。主要研究碱金属原子“临界SERF态”机制，分析原子极化率、温度和磁场强度对其自旋状态的影响规律。研究碱金属原子拉莫尔进动频率与磁共振线宽的关系，获得“临界SERF态”快速、精确判定方法。研究多因素对碱金属原子“临界SERF态”综合作用，确立最佳调控方案。采用“零磁信号跟踪法”，实现非屏蔽条件下原子“临界SERF态”，既放宽了SERF效应苛刻条件，又使磁传感器达到与SERF态相近的磁测灵敏度水平（优于10fT/Hz1/2），适用于野外复杂环境下的弱磁探测，解决了传感器高灵敏度与环境适应性之间的矛盾。

原子无自旋交换弛豫（SERF）效应抑制因自旋交换碰撞引起的量子噪声，可应用于深地资源电磁探测、生物医学磁图成像等领域获取微弱磁场信息。本项目提出一种“临界SERF态”原子磁传感原理，能够在非屏蔽条件下实现三轴矢量高灵敏度磁测量。深入研究了碱金属原子“临界SERF态”机制，通过分析原子极化率、温度和磁场强度对其自旋状态的影响规律实现“临界SERF态”自旋弛豫优化，探明碱金属原子拉莫尔进动频率与磁共振线宽的关系，获得“临界SERF态”快速、精确判定方法。设计间断电无磁加热系统保证碱金属原子工作在无磁干扰环境下，同时提出的激光器稳频技术可以使激光器稳定工作在碱金属原子的最佳泵浦频率上，设计的大范围低噪声线圈驱动电流源让磁力仪脱离了传统的屏蔽筒环境，结合非屏蔽装置和主动磁补偿算法使磁传感器达到与SERF态相近的磁测灵敏度水平（优于100fT/Hz1/2）。