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: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=656113
• 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.

准确了解支配和塑造宇宙的基本力量不仅对于基础科学而且对于技术突破都至关重要。该提案为利用冷原子精确测量各种基本力的广泛研究项目寻求运营资金。该提案的主要科学目标是：精确测量重力加速度g、精确测量电磁力强度（精细结构常数）和精确测量原子磁性（g因子比）。所有这些实验最近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提高精度，这将在不久的将来带来一系列具有国际竞争力的精密测量。**原子干涉仪 (AI) 依赖于冷原子的波动性质和对物质波的复杂控制通过充当分束器和镜子的激光脉冲。通过这种方式，与使用材料元素分裂和重组光的传统光学干涉仪相比，光和物质的角色互换了。通过增加原子波时空路径的封闭面积以及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，可以增强人工智能的灵敏度。约克大学使用低成本设备改进了独特的回声型人工智能，以实现 250 毫秒的测量时间尺度，这与斯坦福大学、伯克利分校、喷气推进实验室的领先国际团体开发的广为人知的拉曼人工智能的时间尺度相当。 MPI、ENS 和波尔多。由于 echo AI 依赖于一种颜色激光激励并且不需要速度选择，因此它降低了精确测量重力加速度 g 的实验复杂性。该提案的一个重要内容将侧重于提高当前使用 50 毫秒测量时间尺度实现的十亿分之 75 (ppb) 的精度水平，并使用 300 毫秒时间尺度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。该计划得到了工业合作伙伴的支持，该合作伙伴是商业重力计的领先制造商。**同一人工智能的不同配置最近使用了 100 毫秒的时间尺度，并展示了通过光传递到原子的动量的 37 ppb 测量结果，可以与原子精细结构常数“α”相关的量。这个通用耦合参数定义了光与物质相互作用的强度。我们建议减少系统影响并实现 0.5 ppb 的精度。在使用独立测量技术定义这一基本常数的国际努力的背景下，这种测量对基础物理学很有意义。**申请人的小组最近对一类特定的磁相互作用进行了最精确的测量，可以用作原子结构的灵敏测试以及比较物质与反物质的磁性。通过精细的实验，我们建议进一步提高精度，避免系统效应并实现100 ppb的精度。 **技术目标将集中于申请人团队开发的自动锁定激光系统的商业应用。