Precision Measurements with Nuclear Spins

在这个项目中，大量的原子将被激光操纵，以便排列它们的磁场。这将允许原子进动频率的高精度测量，以解决几个实际和基本的物理问题。其中一个问题是，宇宙中是否充满了被称为暗物质的看不见的粒子，这种粒子与普通原子的相互作用非常微弱。如果存在这样的粒子，它们可以改变原子进动的频率。将开发新的测量技术来提高实验对这种相互作用的灵敏度。另一个问题是，放置在真空中的原子是否有特定的优先取向方向。原子进动频率的灵敏测量也可用于检测非常弱的磁场，并可用于空间定向。本项目将探讨这些实际应用中的基本灵敏度限制问题。具有长自旋相干时间的极化核自旋的大集合将用于若干精度测量。将开发一种连续流动液体Xe-129磁力计，用于寻找与暗物质粒子可能发生的共振相互作用。He-3-Ne-21共磁力计将用于寻找非常轻的暗物质粒子和测试局部洛伦兹不变性。将研制一种具有高带宽和长期稳定性的Rb-Ne共磁强计，用于寻找新的远程自旋相关力。在每个系统中，将详细研究密集自旋极化系综之间的相互作用，以便接近自旋共磁仪的基本量子极限，并允许在精密自旋传感的实际应用中取得进一步的进展。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In this project, large collections of atoms will be manipulated with laser light in order to align their magnetic fields. This will allow high precision measurements of the atomic precession frequencies to address several practical and fundamental physics questions. One question is whether the Universe is filled with invisible particles, called dark matter, which only interact very weakly with ordinary atoms. If such particles exist, they can modify the atomic precession frequencies. New measurement techniques will be developed to increase the sensitivity of the experiment to such interactions. Another question is whether atoms placed in empty space have a certain preferred orientation direction. Sensitive measurements of the atomic precession frequencies can also be used to detect very weak magnetic fields and can be used for spatial orientation. The question of fundamental sensitivity limits in these practical applications will be explored during the project.Large ensembles of polarized nuclear spins with long spin coherence times will be used for several precision measurements. A continuous-flow liquid Xe-129 magnetometer will be developed to search for possible resonant interactions with dark matter particles. A He-3-Ne-21 co-magnetometer will be developed to search for very light dark matter particles and for tests of local Lorentz invariance. A Rb-Ne co-magnetometer with high bandwidth and improved long-term stability will be developed to search for new long-range spin dependent forces. In each system the interactions between dense spin-polarized ensembles will be studied in detail in order to approach the fundamental quantum limits of spin co-magnetometers and to allow further advances in practical applications of precision spin sensing.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.