氦-3极化原子的长相干时间、高极化率及高灵敏度检测方法研究

Polarized helium-3 atoms have the advantages of long coherence time and high polarization. However, in fact, light or magnetic field or gas cell materials decrease the key indicators, and there are the magnitude discrepancies between theory and experimental results. This project will develop the Metastability Exchange Optical Pumping (MEOP) model to analyze the light or magnetic-field or atomic/ molecular collisions effects on coherence time and polarization for polarized helium-3 atoms, and adopt the paramagnetic resonance theory to analyze the negative effects on coherence time from the transitional paramagnetic atoms or ions in gas cell materials, and adopt the density-functional model to analyze the positive effects on coherence time from coating materials on surface of gas cell. This physical mechanics researches can direct the manufacture of polarized helium-3 atom cells with long coherence time and high polarization. Furthermore, some common key technologies including adjusting laser linewidth and space modes and radio-frequency quantum detection are developed.

氦-3极化原子理论上具备长相干时间和高极化率优点，但实验发现光、磁场以及气室材料等会降低这两项关键指标，理论与实验有数量级差异。本项目将发展亚稳态与基态原子的自旋交换光泵(Metastability Exchange Optical Pumping , MEOP)理论模型综合分析光、磁场、气体原子或分子之间碰撞对极化原子相干时间和极化率影响；采用顺磁共振理论分析气室材料中过渡族顺磁性原子或离子对相干时间的负面影响；采用密度泛函模型 (density-functional model)分析气室内壁金属膜材料对相干时间的正面影响。这些物理机理研究可指导高极化率和长相干时间的氦-3原子气室的设计和制作，并发展利用激光线宽、空间模式调控原子极化和高灵敏度RF射频量子检测等关键技术。

本项目研究了氦原子亚稳态与基态的交换碰撞过程，从交变磁场引起的缀饰自旋效应，研究了亚稳态交换碰撞的传递效果，实验和理论证明了氦3原子的基态缀饰自旋效应可以相干传递到氦-3原子或氦-4原子的亚稳态，进一步，发现了由高阶原子极矩引起的二阶缀饰自旋效应。本项目利用光频移效应，发明了一种新的自稳定激光频率的原子磁力仪方案；也利用光频移产生的虚磁场效应，实现了一种新的无射频线圈全光氦原子磁力仪。为了检测氦原子磁共振微弱磁场信号，本项目发展了碱金属气室镀石蜡膜方法，解决因气壁与极化原子碰撞造成的退相干问题，并在镀石蜡膜的K-Rb混合泡中研究了不同种碱金属元素之间的自旋交换效应，该技术能够实现无功率依赖、无光频移的磁共振信号，在国际上第一次研制了窄线宽的镀膜混合原子气室。