Search for the Electron EDM Using Cs and Rb in Optical Lattice Traps

寻找光晶格陷阱中使用 Cs 和 Rb 的电子 EDM

• 批准号: 1607517
• 负责人: David Weiss
• 金额: $ 56.89万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1607517&HistoricalAwards=false
• 关键词: Search; Electron; EDM; Using; Cs

The existence of an elementary particle with a permanent electric dipole moment (EDM) would imply that the basic equations of physics are different when time is reversed or all spatial coordinates (parity) are inverted. Although these symmetries are an integral part of classical physics, both are known to be violated in the current "Standard Model" of particle physics. In fact, there have been many direct observations of parity violation, and several indirect measurements of time reversal symmetry breaking. EDMs, however, have yet to be observed. The major motivation for trying to observe EDMs is that most proposed extensions to the Standard Model (such as supersymmetry) predict EDMs that are in the vicinity of the current experimental upper limit, whereas the Standard Model predicts that they should be much smaller. Increasing the precision of experiments could rule out possible extensions to the Standard Model, or provide the first experimental result that cannot be incorporated into the Standard Model. As such it would be a harbinger of a theoretical revolution. To measure the electron EDM, cesium atoms will be cooled with laser beams and trapped with light, and then their internal energy states will be measured in a very large electric field in a very low magnetic field environment. Undergraduates and graduate students will be trained in the use of these tools, which have many applications beyond this measurement.The electron EDM will be searched for in this experiment using laser-cooled cesium atoms. The apparatus construction part of the experiment will be completed and data collection will commence. In the experiment, atoms are loaded into a pair of parallel one-dimensional far-off-resonant optical lattice traps in a magnetically shielded region of space, laser-cooled and optically pumped. Similar to the way permanent magnetic dipole measurements are routinely measured by looking for linear Zeeman energy shifts in magnetic fields, the EDM will be searched for by looking for linear Stark shifts in an electric field. The experiment is designed to be insensitive to magnetic fields and magnetic field gradients by simultaneously measuring two sets of atoms that experience opposite electric fields. It is projected that the experiment will be sensitive to an EDM as small as 3x10-30 e-cm, which is a 30-fold improvement over the current limit. In parallel to making the EDM experiment fully operational, the group will perform a related technological study to try to maximize the electric fields that can be sustained with the conducting oxide coated glass plates that are used. Along the way, there are two atomic polarizability measurements that the apparatus is uniquely configured to measure with improved sensitivity. Before incorporating improved field plates, the group will likely perform these measurements, which can provide tests of atomic calculations and possible improvements to the understanding of cesium clock shifts.

具有永久电偶极矩（EDM）的基本粒子的存在意味着，当时间反转或所有空间坐标（宇称）反转时，物理基本方程会有所不同。 尽管这些对称性是经典物理学不可或缺的一部分，但众所周知，在当前的粒子物理学“标准模型”中，这两种对称性都被违反了。事实上，已经有许多关于宇称不守恒的直接观察，以及一些关于时间反转对称性破缺的间接测量。然而，EDM 尚未被观察到。尝试观察 EDM 的主要动机是，大多数提出的标准模型扩展（例如超对称性）预测 EDM 位于当前实验上限附近，而标准模型预测它们应该小得多。提高实验的精度可能会排除对标准模型的可能扩展，或者提供无法纳入标准模型的第一个实验结果。因此，这将是一场理论革命的先兆。为了测量电子电火花，铯原子将被激光束冷却并被光捕获，然后在非常低的磁场环境中的非常大的电场中测量它们的内部能态。本科生和研究生将接受使用这些工具的培训，这些工具除了测量之外还有许多应用。在本实验中，将使用激光冷却铯原子来探索电子放电加工。 实验的仪器搭建部分将完成并开始数据收集。在实验中，原子被加载到空间磁屏蔽区域中的一对平行一维远非共振光晶格陷阱中，并进行激光冷却和光泵浦。 与通过寻找磁场中的线性塞曼能量位移来常规测量永磁偶极子测量的方式类似，将通过寻找电场中的线性斯塔克位移来搜索 EDM。该实验旨在通过同时测量两组经历相反电场的原子，对磁场和磁场梯度不敏感。预计该实验将对小至 3x10-30 e-cm 的 EDM 敏感，这比当前限制提高了 30 倍。在使 EDM 实验全面投入运行的同时，该小组还将进行相关的技术研究，试图最大限度地提高所使用的导电氧化物涂层玻璃板可以维持的电场。在此过程中，有两个原子极化率测量，该设备经过独特配置，可以提高灵敏度进行测量。在采用改进的场板之前，该小组可能会进行这些测量，这可以提供原子计算的测试，并可能改进对铯钟偏移的理解。