PM: Measuring Gravity at the Micron-Scale with Laser-Cooled Trapped Microspheres: A Renewal Proposal

PM：用激光冷却捕获微球测量微米级重力：更新提案

• 批准号: 2110524
• 负责人: Andrew Geraci
• 金额: $ 42万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-15 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2110524&HistoricalAwards=false
• 关键词: PM; Measuring; Gravity; Micron; Scale

Gravity is the least well understood of the four known fundamental forces in Nature. Its weakness when compared to the other three Standard Model forces makes gravity particularly challenging to measure precisely in experiments. There have been several predictions from theories beyond the Standard Model of particle physics, including string theory and supersymmetry, that the Newtonian gravitational inverse square law will break down at some distance below the millimeter scale. To put these theories to the test, a method using an optically-trapped laser-cooled glass bead as a test mass and a microfabricated silicon and gold device as a source mass has been developed. When surrounded by a high-vacuum environment, the glass bead experiences very little friction and becomes an ultraprecise force measurement instrument, needed to measure feeble gravitational interactions between objects at such close ranges. At the same time, scanning and screening methods are employed to eliminate systematic effects from undesired electromagnetic background forces. It is estimated that the method can improve the search for corrections to the gravitational inverse square law at the micron length scale by more than three orders of magnitude. One graduate student and one postdoctoral researcher will be broadly trained in experimental physics and nanofabrication. By participating in this highly interdisciplinary research project, students will be well equipped for scientific careers, and efforts to include researchers from under-represented minorities will be undertaken. The fundamental nature of this project can instill a sense of wonder about the natural world in the general public. The nation will benefit from an improved understanding of high-energy physics related to gravitational physics at the micron length scale, at a fraction of the cost of particle-collider experiments. In this project, an experiment will continue to be developed which makes use of laser-cooled trapped microspheres to test for Yukawa-type deviations from Newtonian gravity at the micron length scale. This new technique can advance the understanding of gravity at this length scale by over three orders of magnitude and may lead to ground-breaking discoveries. Building on previous results, including calibrated zeptonewton force sensitivity and the development of techniques to reliably maneuver nanospheres in three-dimensions within micron-distances from a source mass surface, the next phase of the project is conceptually divided into two tasks: (1) investigation of systematic errors in preliminary gravity measurements, with a goal of acquiring millions of integrated data in a dedicated Yukawa-force search at the ∼ 1 μm-scale, and (2) in-parallel development of novel methods for trapping and cooling the levitated nanoparticles, including sympathetic cooling with cold atoms.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.

引力是自然界已知的四种基本力中最不为人所知的。 与其他三种标准模型力相比，它的弱点使得在实验中精确测量重力特别困难。粒子物理学标准模型之外的理论（包括弦理论和超对称性）已经做出了一些预测，即牛顿引力平方反比定律将在毫米级以下的某个距离处失效。为了检验这些理论，开发了一种使用光捕获激光冷却玻璃珠作为测试质量和微加工硅和金器件作为源质量的方法。当被高真空环境包围时，玻璃珠受到的摩擦力非常小，成为超精密力测量仪器，需要在如此近距离的范围内测量物体之间的微弱重力相互作用。 同时，采用扫描和筛选方法来消除不良电磁背景力的系统影响。据估计，该方法可以将微米长度尺度上引力平方反比定律的修正搜索改进三个数量级以上。一名研究生和一名博士后研究员将接受实验物理和纳米制造方面的广泛培训。通过参与这个高度跨学科的研究项目，学生将为科学职业做好充分准备，并将努力吸纳来自代表性不足的少数族裔的研究人员。该项目的基本性质可以向公众灌输对自然世界的好奇心。国家将受益于对与微米长度尺度的引力物理相关的高能物理的更好的理解，而成本只是粒子对撞机实验的一小部分。在该项目中，将继续开发一项实验，利用激光冷却捕获的微球来测试微米长度尺度上与牛顿重力的汤川型偏差。这项新技术可以将在这个长度尺度上对重力的理解提高三个数量级以上，并可能带来突破性的发现。基于先前的成果，包括校准的 zeptonewton 力灵敏度和开发在距源质量表面微米距离内的三维可靠操纵纳米球的技术，该项目的下一阶段在概念上分为两个任务：（1）调查初步重力测量中的系统误差，目标是在专用的汤川力中获取数百万个综合数据 〜1微米尺度的搜索，以及（2）并行开发捕获和冷却悬浮纳米颗粒的新方法，包括用冷原子进行交感冷却。该奖项反映了美国国家科学基金会的法定使命，并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。

项目成果

Scanning force sensing at micrometer distances from a conductive surface with nanospheres in an optical lattice

使用光学晶格中的纳米球在距导电表面微米距离处扫描力传感

• DOI: 10.1364/ao.457148
• 发表时间: 2022
• 期刊: Applied Optics
• 影响因子: 1.9
• 作者: Montoya, Cris;Alejandro, Eduardo;Eom, William;Grass, Daniel;Clarisse, Nicolas;Witherspoon, Apryl;Geraci, Andrew A.
• 通讯作者: Geraci, Andrew A.

An apparatus for in-vacuum loading of nanoparticles into an optical trap

一种将纳米粒子真空装载到光阱中的装置

• DOI: 10.1063/5.0118083
• 发表时间: 2022
• 期刊: Review of Scientific Instruments
• 影响因子: 1.6
• 作者: Weisman, Evan;Galla, Chethn Krishna;Montoya, Cris;Alejandro, Eduardo;Lim, Jason;Beck, Melanie;Winstone, George P.;Grinin, Alexey;Eom, William;Geraci, Andrew A.
• 通讯作者: Geraci, Andrew A.