Cs Energy Shifts in an Electric Field

电场中铯能量的变化

• 批准号: 1912577
• 负责人: David Weiss
• 金额: $ 48.9万
• 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: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1912577&HistoricalAwards=false
• 关键词: Cs; Energy; Shifts; Electric; Field

There is a long, fruitful history of precision measurements in low energy physics being used to answer questions that are usually considered the realm of high energy particle physics. For instance, precision atomic parity non-conservation experiments constrain the electroweak theory in a way that is inaccessible to particle accelerators. Another example is the search for a permanent electric dipole moment (EDM) in atoms and molecules. If an EDM were to be discovered, it would imply that the standard model of physics is incomplete, and it would point the way to a more overarching theory. The atomic measurement proposed here relates to both of these examples. The best atomic parity violation measurement uses atomic cesium in electric and magnetic fields. To extract the fundamental physics, it is necessary to disentangle the atomic physics from the atomic measurement. For about 20 years, full advantage could not be taken of the best parity violation measurement, because the atomic theory tools were not good enough. Recent theoretical advances are starting to change that, but the tools need independent validation. This project will measure a different property of cesium in an electric field, its ground state tensor polarizability (GSTP), improving the experimental knowledge of that value by a factor of at least 25. The calculations needed for the cesium parity violation result are similar to those needed to predict the GSTP, so these measurements will help validate the atomic theory with the required precision. The GSTP measurements are also similar enough to those needed for a cesium EDM search that they will be a step along the way toward completing such a measurement. The experiment will also train graduate students in a very wide range of experimental and theoretical methods.The cesium GSTP (and ultimately the cesium EDM) will be measured using laser-cooled Cs atoms trapped in a pair of parallel 1D far-off-resonant optical lattice traps in a magnetically shielded region of space. The experiment is designed around being able to separately measure the populations of each ground state magnetic sublevel. Within the same set of atoms, direct transitions between adjacent positive magnetic sublevels can be measured at the same time as transitions between adjacent negative magnetic sublevels. In a 750 microGauss magnetic field and a 33 kV/cm electric field, these two transitions will differ by an amount that is proportional to the GSTP, ~20 Hz. The pulse-time-limited linewidth will be 1 Hz, so the line splitting that can be readily achieved with the available 108 atoms will yield ~10-4 sensitivity in a single scan. The ultimate precision will be limited by systematic affects related to the light traps. These can clearly be controlled well enough to improve on the existing 8% relative precision by a factor of 25. The fact that the new GSTP measurement directly measures transitions between ground state sublevels accounts for the large expected improvement over previous measurements, which looked for small shifts in much broader optical transitions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

低能物理学中的精密测量被用来回答通常被认为是高能粒子物理学领域的问题，有着悠久而富有成果的历史。例如，精密原子宇称非守恒实验以粒子加速器无法实现的方式限制了电弱理论。 另一个例子是寻找原子和分子中的永久电偶极矩（EDM）。如果发现了 EDM，则意味着物理学的标准模型是不完整的，并且它将为更全面的理论指明道路。这里提出的原子测量涉及这两个例子。最好的原子宇称不守恒测量使用电场和磁场中的原子铯。为了提取基础物理学，有必要将原子物理学与原子测量分开。大约 20 年来，由于原子理论工具不够好，无法充分利用最好的宇称不守恒测量。最近的理论进展开始改变这一点，但这些工具需要独立验证。该项目将测量铯在电场中的不同特性，即其基态张量极化率 (GSTP)，将该值的实验知识提高至少 25 倍。铯宇称违反结果所需的计算类似于预测 GSTP 所需的数据，因此这些测量将有助于以所需的精度验证原子理论。 GSTP 测量也与铯 EDM 搜索所需的测量非常相似，因此它们将是完成此类测量的一个步骤。该实验还将对研究生进行广泛的实验和理论方法的培训。铯 GSTP（以及最终的铯 EDM）将使用捕获在一对平行一维远离共振光学器件中的激光冷却 Cs 原子进行测量空间磁屏蔽区域中的晶格陷阱。 该实验的设计目的是能够单独测量每个基态磁子能级的数量。在同一组原子内，可以同时测量相邻正磁性子能级之间的直接跃迁和相邻负磁性子能级之间的跃迁。在 750 微高斯磁场和 33 kV/cm 电场中，这两个转变的差异量与 GSTP（约 20 Hz）成正比。脉冲时间限制的线宽将为 1 Hz，因此可以使用可用的 108 个原子轻松实现线分裂，从而在单次扫描中产生约 10-4 的灵敏度。最终精度将受到与光阱相关的系统影响的限制。显然，这些可以得到足够好的控制，可以将现有 8% 的相对精度提高 25 倍。事实上，新的 GSTP 测量直接测量基态子能级之间的转变，这与以前的测量相比，预期有很大的改进，而以前的测量只需要很小的改进。该奖项反映了 NSF 的法定使命，并且通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。