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: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=610809
• 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.

对支配和塑造我们宇宙的基本力量的精确认识不仅对基础科学至关重要，而且对技术突破也至关重要。该提案寻求为利用冷原子精确测量各种基本力的广泛研究计划提供运营资金。该提案的主要科学目标是：精确测量重力加速度g，精确测量电磁力的强度（精细结构常数）和精确测量原子的磁性（g因子比）。最近，所有这些实验都达到了与使用独特的原子干涉和相干瞬态技术的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精度提高将在不久的将来导致一系列具有国际竞争力的精度测量。 原子干涉仪（AI）依赖于冷原子的波动性质和作为分束器和镜子的激光脉冲对物质波的复杂控制。以这种方式，光和物质的作用与传统的光学干涉仪相比互换，传统的光学干涉仪使用材料元件来分离和重组光。通过增加原子波时空路径的封闭区域和观察仅受原子通过激光束的渡越时间限制的扩展时间尺度上的干涉效应，增强了AI的灵敏度。在约克大学，一种独特的回波型AI已经使用低成本设备进行了改进，以实现250 ms的测量时间尺度，这与斯坦福大学、伯克利、喷气推进实验室、MPI、ENS和波尔多的领先国际团体开发的广为人知的拉曼AI的时间尺度相当。由于回波AI依赖于单色激光激发，并且不需要速度选择，因此它为精确测量重力加速度g提供了降低的实验复杂性。本提案的一个重要内容将侧重于提高目前使用50毫秒测量时标达到的十亿分之75的精度水平，并使用300毫秒时标达到具有国际竞争力的精度水平（0.5 ppb）。重力测量的重要性与其校准工业重力仪的潜力有关，工业重力仪在矿产、石油和天然气等自然资源勘探、潮汐图校正和地震监测中发挥着普遍作用。这一举措得到了一个工业合作伙伴的支持，该合作伙伴是商业重力仪的领先制造商。 同一人工智能的不同配置最近使用了100 ms的时间尺度，并证明了光传递到原子的动量的37 ppb测量值，该量可以与原子精细结构常数“alpha”相关。这个普适耦合参数定义了光-物质相互作用的强度。我们建议减少系统的影响，实现0.5 ppb的精度。这种测量是感兴趣的基础物理学的背景下，国际努力定义这个基本常数使用独立的测量技术。 申请人的小组最近对一类特殊的磁相互作用进行了最精确的测量，这种磁相互作用可用作原子结构的灵敏测试，并用于比较物质与反物质的磁性。使用一个精致的实验，我们建议进一步提高精度，避免系统的影响，实现100 ppb的准确度。 技术目标将侧重于申请人小组开发的自动锁定激光系统的商业应用。