GOALI: Synchronously Pumped NMR Oscillator

该项目是威斯康星大学麦迪逊分校与诺斯罗普-格鲁曼公司的科学家和工程师合作的项目，将进一步开发超高灵敏度核磁共振(核磁共振)的新概念。这个想法是对由于磁场、惯性旋转或假设的与自旋相关的自然新力而导致的核自旋运动进行精确测量。值得注意的是，这种测量既有实际影响(例如用于导航的微型陀螺仪)，也可以用来测试与宇宙中暗物质有关的新想法。这是一个潜在的实用装置的例子，它利用量子力学的基本特征来测量运动的宏观性质。该项目的基本原理依赖于核磁共振偏置磁场的应用，其形式为一系列定义明确的区域的短脉冲，与随时间变化的光学泵浦相结合，允许碱原子和惰性气体原子核以相同的频率前进，尽管其磁矩相差3个数量级。这两个物种都是极化的，并且完全横穿偏置场。这大大抑制了已知的影响此类仪器传统设计的主要系统误差，但保留了使用嵌入式碱性磁强计超灵敏读出核磁共振进动的好处。对技术噪声的估计表明，该系统的潜在频率噪声水平好于10nHz/平方赫兹(赫兹)，基本限制要好得多。以前的工作已经展示了该系统的基本特性；该项目将研究系统误差并改善统计不确定度。该系统将作为一个工业合作伙伴非常感兴趣的精密核磁共振陀螺仪进行测试，并将用于在搜索轴子类粒子时设置新的质量和灵敏度限制。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project, a collaborative project between the University of Wisconsin-Madison and scientists and engineers at Northrop-Grumman Corporation, will further develop new concepts in ultrahigh sensitivity nuclear magnetic resonance (NMR). The idea is make precise measurements of the motions of nuclear spins due to magnetic fields, inertial rotations, or hypothetical new spin-dependent forces of nature. It is noteworthy that such measurements have both practical impact (miniature gyroscopes for navigation, for example) and can be used to test new ideas related to dark matter in the universe. This is an example of a potentially practical device that uses basic features of quantum mechanics to make measurements of macroscopic properties of motion. The underlying principles of the project rely on the application of NMR bias magnetic fields in the form of a sequence of short pulses of well-defined areas that act, in concert with time-dependent optical pumping, to allow alkali atoms and noble-gas nuclei to precess at the same frequency despite having magnetic moments that are different by 3 orders of magnitude. Both species are polarized and precess entirely transverse to the bias field. This greatly suppresses the dominant systematic errors that are known to affect traditional designs of such instruments, but retains the benefits of ultra-sensitive readout of the NMR precession using the embedded alkali magnetometer. Estimates of technical noise indicate the system has a potential frequency noise level of better than 10 nHz/sqrt(Hz), with fundamental limits that are much better. Previous work has demonstrated the basic properties of this system; this project will study systematic errors and improve the statistical uncertainties. The system will be tested as a precision NMR gyro, of great interest to the industrial partners, and will be used to set new mass and sensitivity limits in searches for axion-like particles.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.