Ultrasensitive Measurements of Forces Using Laser-Cooled Atoms

精确了解支配和塑造我们宇宙的基本力量不仅对基础科学至关重要，对技术突破也是至关重要的。这项提议为一项广泛的研究计划寻求业务资金，该计划利用冷原子对各种基本力量进行精确测量。该提议的主要科学目标是：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)和精确测量原子的磁性(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变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改进将在不久的将来导致一系列具有国际竞争力的精确测量。原子干涉仪(AIS)依赖于冷原子的波动性质，并通过充当分束器和反射镜的激光脉冲来复杂地控制物质波。以这种方式，与传统的光学干涉仪相比，光和物质的作用是互换的，传统的光学干涉仪使用材料元素来分解和重新组合光。通过增加原子波时空路径的封闭面积，以及在仅受原子通过激光的时间限制的扩展时间尺度上观察干涉效应，增强了人工智能的灵敏度。在约克大学，一种独特的回声类型人工智能已经使用低成本仪器进行了改进，实现了250毫秒的测量时间刻度，这与斯坦福大学、伯克利大学、喷气推进实验室、MPI、ENS和波尔多的领先国际集团开发的广为人知的拉曼人工智能的时间刻度相当。由于ECHO AI依赖于单色激光激励且不需要速度选择，因此它为精确测量重力加速度g提供了更低的实验复杂性。这项建议的一个重要内容将侧重于提高目前使用50 ms测量时间刻度实现的75 ppb的精度水平，并使用300 ms时间刻度达到具有国际竞争力的精度水平(0.5 ppb)。重力测量的意义与它们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的勘探、潮汐图校正和地震监测中发挥着普遍作用。这一倡议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。同一人工智能的另一种配置最近利用了100毫秒的时间尺度，并展示了通过光传递给原子的动量的37 ppb测量，这个量可以与原子精细结构常数“α”有关。这个普遍的耦合参数定义了光-物质相互作用的强度。我们建议减少系统影响，实现0.5 ppb的精度。在使用独立测量技术定义这一基本常量的国际努力的背景下，这种测量对基础物理学是有意义的。申请人的团队最近对一类特殊的磁相互作用进行了最精确的测量，这类磁相互作用可用作原子结构的灵敏测试，并用于比较物质和反物质的磁性。通过改进实验，我们建议进一步提高精度，避免系统影响，实现100 ppb的精度。技术目标将集中在申请者团队开发的自动锁定激光系统的商业应用上。

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.