Ultrasensitive Measurements of Forces Using Laser-Cooled Atoms

使用激光冷却原子对力进行超灵敏测量

• 批准号: RGPIN-2014-04063
• 负责人: Kumarakrishnan, Anantharaman
• 金额: $ 2.11万
• 依托单位: York University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633128
• 关键词: Ultrasensitive; Measurements; Forces; Using; Laser

Precise knowledge of the basic forces that govern and shape our universe is of paramount importance not only for fundamental science, but also for technological breakthroughs. This proposal seeks operational funding for a broad research program utilizing cold atoms for the precision measurements of a variety of basic forces. The main scientific goals of the proposal are: precision measurement of the gravitational acceleration g, precision measurement of the strength of the electromagnetic force (the fine-structure constant) and the precision measurement of the magnetic properties of atoms (g-factor ratios). All these experiments have recently achieved levels of precision associated with leading techniques using distinctive atom interferometric and coherent transient techniques. Results suggest that improvements in accuracy that can be achieved by addressing systematic effects will lead to a series of internationally competitive precision measurements in the near future.Atom interferometers (AIs) rely on the wave nature of cold atoms and intricate control of matter waves by pulses of laser light that act as beam splitters and mirrors. In this manner, the roles of light and matter are interchanged in comparison with traditional optical interferometers that use material elements to split and recombine light. The sensitivity of AIs are enhanced by increasing the enclosed area of space-time paths of atomic waves and by observing interference effects on extended time scales that are limited only by the transit time of atoms through laser beams. At York University a unique, echo type AI has been refined using a low cost apparatus to achieve measurement time scales of 250 ms, which is comparable to the time scales of widely known Raman AIs developed by leading international groups at Stanford, Berkeley, JPL, MPI, ENS and Bordeaux. Since the echo AI relies on one color laser excitation and does not require velocity selection, it offers reduced experimental complexity for precise measurements of gravitational acceleration g. An important element of this proposal will focus on improving the current level of precision of 75 parts per billion (ppb) achieved using a 50 ms measurement time scale and reaching an internationally competitive level of accuracy (0.5 ppb) using a 300 ms time scale. The significance of gravity measurements is related to their potential for calibrating industrial gravimeters that play an ubiquitous role in the exploration of natural resources such as minerals, petroleum, and natural gas, in the correction of tidal charts, and seismic monitoring. This initiative is supported by an industrial partner who is the leading manufacturer of commercial gravimeters.A different configuration of the same AI recently utilized a time scale of 100 ms and demonstrated a 37 ppb measurement of the momentum transferred to atoms by light, a quantity that can be related to the atomic fine structure constant "alpha". This universal coupling parameter defines the strength of light-matter interactions. We propose to reduce systematic effects and realize an accuracy of 0.5 ppb. This measurement is of interest to basic physics in the context of an international effort to define this fundamental constant using independent measurement techniques.The applicant's group has recently made the most precise measurement of a particular class of magnetic interactions that can be used as a sensitive test of atomic structure and for comparing the magnetic properties of matter with antimatter. Using a refined experiment, we propose to further improve the precision, avoid systematic effects and realize an accuracy of 100 ppb.Technological goals will focus on commercial applications of auto-locked laser systems developed by the applicant's group.

对管理和塑造我们宇宙的基本力量的精确知识不仅对基本科学，而且对技术突破至关重要。该提案寻求利用冷原子的广泛研究计划进行运营资金，以精确测量各种基本力量。该提案的主要科学目标是：重力加速G的精确测量，电磁力强度的精度测量（细结构常数）和原子磁性特性的精确测量（G-FACTOR比率）。最近，使用独特的原子干涉和相干瞬态技术，所有这些实验都达到了与领先技术相关的精度水平。结果表明，通过解决系统效应可以实现的准确性的提高将在不久的将来导致一系列国际竞争性的精度测量值。ATOM干涉仪（AIS）依赖于冷原子的波性质以及通过激光光的脉冲来控制物质波的波动性质，这些激光光的脉冲充当光束隔板和镜像。通过这种方式，与传统的光学干涉仪相比，光和物质的作用互换，这些光学干涉仪使用材料元素进行分裂和重组光。通过增加原子波的时空路径的封闭区域以及观察到仅受激光束原子的过渡时间限制的长时间尺度的干扰效应来增强AIS的敏感性。在York University，使用低成本设备对AI的独特，Echo型AI进行了改进，以实现250毫秒的测量时间尺度，这与由斯坦福大学，伯克利，JPL，MPI，ENS和Bordeaux的领先国际群体开发的广为著名的Raman AIS的时间尺度相媲美。由于ECHO AI依赖于一种颜色激发，并且不需要速度选择，因此它提供了降低的实验复杂性，用于精确测量引力加速度g。该提案的一个重要要素将重点侧重提高使用50 ms的测量时间尺度达到的当前数十亿（PPB）的精确度，并使用300毫秒的时间尺度达到国际竞争性准确性（0.5 ppb）。重力测量的重要性与它们校准工业重量表的潜力有关，这些工业重量表在探索矿物质，石油和天然气等自然资源中起着无处不在的作用，在校正潮汐图和地震监测方面起着无处不在的作用。该计划得到了一个工业合作伙伴的支持，该工业合作伙伴是商业重量表的领先制造商。同一AI的不同配置最近使用了100毫秒的时间尺度，并证明了通过光转移到原子的37 ppb测量，该数量可以与原子良好的结构常数“ alpha”相关。该通用耦合参数定义了光 - 物质相互作用的强度。我们建议降低系统效应并实现0.5 ppb的准确性。在国际努力下，使用独立的测量技术定义了这种基本常数的背景下，这种测量值对基本物理学感兴趣。申请人的小组最近对特定的磁相互作用类别进行了最精确的测量，可以用作原子结构的敏感测试，并将其比较物质的磁性特性与反物质进行比较。使用精致的实验，我们建议进一步提高精度，避免系统效应并实现100 ppb的准确性。技术目标将集中在申请人组开发的自动锁激光系统的商业应用上。