Measuring the electron electric dipole moment using an array of ultracold molecules

使用超冷分子阵列测量电子电偶极矩

基本信息

批准号：
ST/V00428X/1
负责人：
Jongseok Lim
金额：
$ 84.61万
依托单位：
Imperial College London
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2021
资助国家：
英国
起止时间：
2021 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FV00428X%2F1
关键词：
Measuring electron electric dipole moment

项目摘要

The Standard Model of particle physics is one of the greatest achievements of modern science. It has been fabulously successful in classifying the fundamental particles and explaining how they behave. Nevertheless, it is widely accepted that the Standard Model is incomplete because it fails to explain several important observations. One prominent example is the excess of matter over antimatter in the universe. The Standard Model predicts almost equal amounts of matter and antimatter, but observations show the universe contains only matter. This contradiction is one of the great unsolved problems in modern physics and a major deficiency of our most fundamental theory.To build a more complete picture of the universe, physicists are striving to reveal what lies beyond the Standard Model. This is an important objective of much of the research being done at gigantic particle accelerators. There is an alternative, and ingenious, way to explore the same problem - measure the shape of an electron. The new forces needed to explain the matter/antimatter imbalance also make electrons slightly non-spherical. This distortion - known as the electric dipole moment - changes the energy of an electron in an electric field, and that tiny change is amplified when the electron is bound to a molecule. I propose to build an apparatus that uses an array of molecules cooled to microkelvin temperatures to make an extremely precise measurement of the electron's shape. With very careful measurements, such table-top experiments enable us to probe energies equal to, or even above, those reached by the particle accelerators. Such marvellous precision has become possible by my recent success in cooling molecules to ultracold temperature. That technique is the foundation of this proposal.My plan is to decelerate a beam of ytterbium monofluoride molecules to rest using the forces exerted by carefully tuned laser light, trap these molecules and cool them to a few microkelvin. Then, I will load them into an array of traps formed by standing waves of light. The array contains millions of individual traps and isolates the molecules from one another, creating a pristine environment for measuring the electron's electric dipole moment. This measurement is done by watching how the spin of the molecules precesses in applied magnetic and electric fields, similar to the precession of a gyroscope or spinning top in a gravitational field. An electric dipole moment changes this precession rate, though only by the tiniest amount. That tiny change is detected more easily if the spin precesses for a long time. Because molecules are confined and isolated in the array, the time can be thousands of times longer than in current experiments. That makes my measurement scheme far more sensitive than any other experiment, allowing me to search for new physics with unprecedented precision.

粒子物理学的标准模型是现代科学最伟大的成就之一。它在对基本粒子进行分类并解释它们的行为方式方面取得了巨大的成功。然而，人们普遍认为标准模型是不完整的，因为它无法解释几个重要的观察结果。一个突出的例子是宇宙中物质多于反物质。标准模型预测物质和反物质的数量几乎相等，但观测表明宇宙只包含物质。这一矛盾是现代物理学中尚未解决的重大问题之一，也是我们最基本理论的主要缺陷。为了构建更完整的宇宙图景，物理学家正在努力揭示标准模型之外的东西。这是在巨型粒子加速器上进行的许多研究的一个重要目标。有另一种巧妙的方法来探索同一问题——测量电子的形状。解释物质/反物质不平衡所需的新力也使电子稍微呈非球形。这种扭曲（称为电偶极矩）会改变电场中电子的能量，当电子与分子结合时，这种微小的变化会被放大。我建议建造一种装置，使用冷却至微开尔文温度的分子阵列来对电子形状进行极其精确的测量。通过非常仔细的测量，这种桌面实验使我们能够探测到等于甚至高于粒子加速器所达到的能量。我最近成功地将分子冷却到超冷温度，使这种惊人的精度成为可能。该技术是该提案的基础。我的计划是利用精心调谐的激光施加的力来减速一氟化镱分子束以使其静止，捕获这些分子并将它们冷却到几微开尔文。然后，我会将它们装入由驻波形成的一系列陷阱中。该阵列包含数百万个单独的陷阱，并将分子彼此隔离，为测量电子的电偶极矩创造了一个原始环境。这种测量是通过观察分子的自旋在施加的磁场和电场中如何进动来完成的，类似于陀螺仪或陀螺在重力场中的进动。电偶极矩改变了进动速率，尽管改变的幅度非常小。如果自旋进动时间较长，那么这种微小的变化就更容易被检测到。由于分子在阵列中被限制和隔离，因此时间可能比当前实验长数千倍。这使得我的测量方案比任何其他实验都更加灵敏，使我能够以前所未有的精度寻找新的物理学。