RUI: Search for Anomalous Spin Interactions with Atomic Comagnetometers

我们的研究计划包括两个不同的项目。第一个项目是对原子自旋和地球质量之间远距离相互作用的实验研究。这种相互作用可能是由于迄今为止未被发现的“第五种力”而产生的，或者如果引力与广义相对论中假设的纯张量相互作用相反，具有标量/伪标量分量。最近的理论研究表明，这种相互作用可能是宇宙加速膨胀的原因，通常归因于暗能量。我们的实验试图通过使用激光光谱同时测量铷的两种同位素的自旋进动来检测这种效应。我们的实验旨在提高实验对远距离自旋-质量相互作用的灵敏度，提高1-3个数量级。我们的第二个项目侧重于为全球奇异物理光学磁力计网络（GNOME）开发原型传感器，这是一组地理上分离的、时间同步的超灵敏原子磁力计，将搜索预示新物理的相关瞬态信号。GNOME对原子核和电子与各种奇异粒子和场的自旋耦合非常敏感。到目前为止，还没有进行过这样的搜索，这使得GNOME成为研究新物理学的一个新的实验窗口。用GNOME探测到的一个具体的、可行的新物理现象的例子，目前不受天体物理观测和实验室实验的约束，是一个由光伪标量场组成的域壁网络。我们目前对基础物理学的理解面临着许多深奥的谜团：宇宙中物质-反物质不对称的起源，暗能量的本质，以及暗物质的本质。我们的实验是在地球上的实验室里进行的，通过对原子自旋的精确测量来检验几种可能解释这些谜团的假设。有人提出，如果我们目前的引力理论是不完整的，那么引力的额外成分既可以产生推动宇宙分离的暗能量，也可以在大爆炸后产生超过反物质的物质。这些额外的重力分量也会导致原子自旋在地球引力场中进动，这就是我们的实验要寻找的效果。对暗物质的一种可能解释是，它是一个由不可见的银河系尺度的“畴壁”组成的网络，它储存着大量的质量和能量。这些看不见的畴壁会对原子自旋施加很小的扭矩，当地球穿过一堵墙时，这种扭矩就可以被探测到。我们正在建造一个原型传感器，对畴壁穿越事件产生的这种扭矩敏感。以我们的原型为基础的时间同步传感器阵列将搜索预示着这种新物理学的天体物理起源的瞬态信号。我们的研究是在一个拥有多元化学生群体的公立本科院校进行的，为许多本科生（包括相当数量的女性和代表性不足的少数民族）提供了最先进的实验物理学的实践经验。

Our research program encompasses two different projects. The first project is an experimental search for a long-range interaction between atomic spins and the mass of the Earth. Such an interaction could arise due to a heretofore undiscovered "fifth force" or if gravity, as opposed to being a purely tensor interaction as assumed in general relativity, has a scalar/pseudoscalar component. Recent theoretical work has shown that such interactions could be the cause of the accelerating expansion of the universe, commonly attributed to dark energy. Our experiment seeks to detect this effect by simultaneously measuring the spin precession of two isotopes of rubidium using laser spectroscopy. Our experiment aims to improve experimental sensitivity to long-range spin-mass interactions by 1-3 orders of magnitude. Our second project focuses on development of a prototype sensor for the Global Network of Optical Magnetometers for Exotic physics (GNOME), an array of geographically separated, time-synchronized ultrasensitive atomic comagnetometers that will search for correlated transient signals heralding new physics. The GNOME would be sensitive to nuclear and electron spin couplings to various exotic particles and fields. To date, no such search has ever been carried out, making the GNOME a novel experimental window on new physics. A specific, feasible example of new physics detectable with the GNOME, presently unconstrained by astrophysical observations and laboratory experiments, is a network of domain walls of light pseudoscalar fields.Our present understanding of fundamental physics is confronted by a number of deep mysteries: the origin of the matter-antimatter asymmetry of the universe, the nature of dark energy, and the nature of dark matter. Our experiments, conducted in laboratories on Earth, use precise measurements of atomic spins to test several hypotheses that might explain these mysteries. It has been proposed that if our present theory of gravity is incomplete, additional components of gravity could both generate the dark energy pushing the universe apart and produce an excess of matter over antimatter after the Big Bang. These additional components of gravity would also cause atomic spins to precess in the Earth's gravitational field, the effect for which our experiment will search. A possible explanation of dark matter is a network of invisible galactic-scale "domain walls" that store considerable mass and energy. These invisible domain walls would exert a small torque on atomic spins that could be detected when the Earth passes through a wall. We are building a prototype sensor sensitive to such torques from domain wall-crossing events. An array of time-synchronized sensors based on our prototype will search for transient signals of astrophysical origin heralding such new physics. Our research is being carried out at a public undergraduate institution with a diverse student body, providing hands-on experience in state-of-the-art experimental physics to many undergraduate students (including a significant number of women and underrepresented minorities).