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

具有永久电偶极矩(EDM)的基本粒子的存在意味着，当时间颠倒或所有空间坐标(宇称)颠倒时，物理学的基本方程是不同的。虽然这些对称性是经典物理学不可分割的一部分，但在目前的粒子物理“标准模型”中，这两个对称性都被认为是被违反的。事实上，已经有许多关于宇称破坏的直接观测，以及几个关于时间反转对称性破坏的间接测量。然而，EDM尚未被观察到。试图观察EDM的主要动机是，大多数对标准模型的扩展(如超对称性)预测EDM在当前实验上限附近，而标准模型预测它们应该小得多。提高实验的精确度可以排除标准模型的可能扩展，或者提供第一个不能并入标准模型的实验结果。因此，这将是一场理论革命的先兆。为了测量电子电火花显微镜，铯原子将被激光冷却并被光俘获，然后在非常低的磁场环境中，在非常大的电场中测量其内部能态。本科生和研究生将接受使用这些工具的培训，这些工具在测量之外还有许多应用。在这个实验中，将使用激光冷却铯原子来寻找电子电火花加工。实验的仪器建造部分将完成，数据收集将开始。在实验中，原子被加载到一对平行的一维远离共振的空间磁屏蔽区的光学晶格陷阱中，激光冷却和光泵浦。类似于通过寻找磁场中的线性塞曼能量移位来常规测量永久磁偶极子测量值的方式，将通过寻找电场中的线性斯塔克移位来搜索EDM。该实验旨在通过同时测量两组经历相反电场的原子来对磁场和磁场梯度不敏感。据预测，该实验将对小至3x10-30e-cm的电火花加工敏感，这是目前限制的30倍。在使电火花加工实验完全投入使用的同时，该小组将进行一项相关的技术研究，试图最大限度地利用所使用的导电氧化物涂层玻璃板所能维持的电场。在此过程中，有两个原子的极化率测量，该仪器被独特地配置为测量具有更高灵敏度的测量。在加入改进的场板之前，该小组可能会进行这些测量，这可以提供原子计算的测试，并可能改进对铯时钟偏移的理解。

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.