Pinpointing with a Broad Beam: h/m and the Fine Structure Constant

用宽光束精确定位：h/m 和精细结构常数

• 批准号: 1806583
• 负责人: Holger Mueller
• 金额: $ 70.5万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1806583&HistoricalAwards=false
• 关键词: Pinpointing; Broad; Beam; Fine; Structure

The fine structure constant characterizes the strength of the electromagnetic interaction and is ubiquitous in physics. It has been measured using methods from across physics, whose agreement is a powerful confirmation of the consistency of theory and experiment. Using well-measured fundamental constants (the Rydberg constant and atomic mass ratios), the fine structure constant can be related to the recoil velocity of an atom that has scattered a photon. This project will use this relationship in order to measure the fine structure constant with the highest precision ever. This will allow the research team to test several extensions of the standard model, such as dark matter candidates, and probe for a substructure of the electron, to test if the electron is indeed an elementary particle. The measurement of the recoil velocity (which is inversely proportional to the atomic mass) can also be used as an ultra-precise realization of the unit of mass and thus a cornerstone of the revised international system of units. This experiment is based on an atom interferometer. It uses a broad laser beam which comes extremely close to the ideal case of an infinite electromagnetic plane wave. A powerful pulsed laser will be available for this project, as well as an atomic fountain accommodating the beam. A new geometry for the atom interferometer will be used, vertically offset simultaneous conjugate interferometers (OSCIs). This will cancel the effects of vibrations, gravity, and even the gravity gradient. The project will measure h/m using a combination of Bragg diffraction and Bloch oscillations with cesium atoms at an accuracy of 0.02 ppb. From h/m, the fine structure constant will be determined with a target accuracy of 0.039 ppb, limited by the accuracy of mAt/me. It is hoped that that improvements in the cesium or electron mass measurement will reduce the error in the fine structure constant to 0.02 ppb. Already now, such measurements of the fine structure constant set stringent limits on several proposed particles. For example, scalar and pseudoscalar bosons, vector bosons, dark photons, hidden-sector photons, and axial-vector bosons would all be discoverable. This tests the standard model of particle physics broadly and deeply.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.

精细结构常数表征了电磁相互作用的强度，在物理学中无处不在。它已经使用跨物理学的方法进行了测量，其一致性是理论和实验一致性的有力证明。使用测量良好的基本常数（里德伯常数和原子质量比），精细结构常数可以与散射光子的原子的反冲速度相关。本项目将利用这种关系，以有史以来最高的精度测量精细结构常数。这将使研究小组能够测试标准模型的几个扩展，例如暗物质候选者，并探测电子的子结构，以测试电子是否确实是基本粒子。反冲速度（与原子质量成反比）的测量也可以用作质量单位的超精确实现，因此是修订后的国际单位制的基石。 这个实验是以原子干涉仪为基础的。它使用一个宽的激光束，非常接近无限电磁平面波的理想情况。一个强大的脉冲激光器将可用于该项目，以及一个原子喷泉容纳光束。将使用一种新的原子干涉仪的几何形状，垂直偏移的同时共轭干涉仪（OSCI）。这将抵消振动、重力甚至重力梯度的影响。该项目将使用铯原子的布拉格衍射和布洛赫振荡相结合来测量h/m，精度为0.02 ppb。从h/m开始，精细结构常数将以0.039 ppb的目标精度确定，受到mAt/me精度的限制。希望铯或电子质量测量的改进将精细结构常数的误差减少到0.02 ppb。现在，精细结构常数的这种测量已经对几种提出的粒子设定了严格的限制。例如，标量玻色子和赝标量玻色子、矢量玻色子、暗光子、隐藏扇区光子和轴矢量玻色子都是可分解的。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Offset simultaneous conjugate atom interferometers

• DOI: 10.1103/physreva.101.053622
• 发表时间: 2019-01
• 期刊: Physical Review A
• 影响因子: 2.9
• 作者: Weicheng Zhong;Richard H. Parker;Z. Pagel;Chenghui Yu;H. Mȕller

Symmetric Bloch oscillations of matter waves

• DOI: 10.1103/physreva.102.053312
• 发表时间: 2020-11-13
• 期刊: PHYSICAL REVIEW A
• 影响因子: 2.9
• 作者: Pagel, Zachary;Zhong, Weicheng;Mueller, Holger
• 通讯作者: Mueller, Holger

Atom‐Interferometry Measurement of the Fine Structure Constant

精细结构常数的原子干涉测量

• DOI: 10.1002/andp.201800346
• 发表时间: 2019
• 期刊: Annalen der Physik
• 影响因子: 2.4
• 作者: Yu, Chenghui;Zhong, Weicheng;Estey, Brian;Kwan, Joyce;Parker, Richard H.;Müller, Holger
• 通讯作者: Müller, Holger

Standard model of particle physics tested by the fine-structure constant

通过精细结构常数测试的粒子物理标准模型

• DOI: 10.1038/d41586-020-03314-0
• 发表时间: 2020
• 期刊: Nature
• 影响因子: 64.8
• 作者: Müller, Holger