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之间的一个产学合作项目，研究了一种使用核磁共振（NMR）进行极其精确和灵敏测量的新方法。 NMR形成了医疗患者可能接受的MRI（磁共振成像）以及各种类型的化学分析的基础。 该项目将研究一种新的NMR方法，该方法被设计用于导航的紧凑型高精度陀螺仪，或用于寻找物质与核自旋之间以前未观察到的力类型的证据。 任何这样观测到的新力量都可能提供关于所谓的“暗物质”性质的重要信息，暗物质被认为构成了宇宙的大部分，但从未被直接观测到。 即使没有检测到这种力，该项目也将对那些试图超越粒子物理学所谓的“标准模型”的理论模型施加限制。 导航的新方法的应用涉及一种可能的手段，使紧凑的基于量子的旋转测量具有前所未有的灵敏度和精度。 作为大学研究人员与工业科学家和工程师之间的合作努力，该项目将促进核自旋在此类测量中的实际应用，促进大学和工业之间的技术转让，并让年轻的研究人员接触到工业研究和开发实验室。基本原理依赖于核磁共振偏置磁场的应用，其形式是一系列短脉冲，限定的区域，其与时间相关的光泵浦一致地起作用，以允许碱金属原子和稀有气体核以相同的频率进动，尽管它们具有相差3个数量级的磁矩。然后，两种物质都可以被极化，并完全横向于偏置场进行进动。这极大地抑制了已知会影响此类仪器的传统设计的主要系统误差，但保留了使用嵌入式碱性磁力计的NMR旋进的超灵敏读出的益处。对技术噪声的估计表明，该系统的潜在频率噪声水平优于每平方根赫兹带宽10纳赫兹，基本限制要好得多。该系统将被用来设置新的严格限制的潜在耦合的轴子到核。 这种方法的基本物理原理现在已经在实验室中得到了证明，关键的系统误差已经被证明至少被抑制了2500倍。 下一步是在双物种实验中实现高灵敏度的承诺，这些实验承诺非常好的磁噪声和漂移抑制。在这种情况下，该系统将作为工业合作伙伴非常感兴趣的精密NMR陀螺仪进行测试，并将用于设置新的质量和灵敏度限制，以寻找轴子状粒子。

This project, an Industry-University Collaborative Project between the University of Wisconsin-Madison and scientists and engineers at Northrop-Grumman Corporation, studies a new approach to making extremely precise and sensitive measurements using Nuclear Magnetic Resonance (NMR). NMR forms the basis for the MRI (magnetic resonance imaging) that a medical patient might receive, and for various types of chemical analysis. This project will investigate a new NMR method designed for use as either a compact, high precision gyroscope for navigation, or for a tool to search for evidence of previously unobserved types of forces between matter and nuclear spins. Any new forces so observed would likely give important information on the properties of so-called "dark matter" which is believed to make up most of the universe but which has never been directly observed. Even if such forces are not detected, the project will place constraints on theoretical models which seek to go beyond the so-called "standard model" of particle physics. The applications of the new method for navigation involve a possible means to make compact quantum-based measurements of rotation with unprecedented sensitivity and accuracy. As a collaborative effort between university researchers and industrial scientists and engineers, the project will promote practical applications of nuclear spins for such measurements, promote technology transfer between university and industry, and expose young researchers to an industrial research and development laboratory.The underlying principles rely on the application of NMR bias magnetic fields in the form of sequences 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 can then be 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 ultrasensitive 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 nano-Hertz per square-root Hertz bandwidth, with fundamental limits that are much better. The system will be used to set new stringent limits on the potential couplings of axions to nuclei. The basic physics principles of this approach have now been demonstrated in the laboratory and the key systematic errors have been shown to be suppressed by at least a factor of 2500. The next steps are to realize the high sensitivity promise in dual-species experiments that promise exceptionally good magnetic noise and drift suppression. In this context the system will be tested as a precision NMR gyroscope, of great interest to the industrial partners, and will be used to set new mass and sensitivity limits in searches for axion-like particles.