RUI: Search for a spin-gravity coupling using laser-addressed atomic gyroscopes

该奖项支持一项实验，以寻找核自旋和地球质量之间的新的远程耦合。根据不同的解释，该实验将改善目前的实验极限多达两个数量级或更多。这种相互作用的存在意味着基本粒子的引力偶极矩（GDM）的存在-它可以被半经典地想象为惯性质量中心和引力质量中心的位置之间的微小分离。GDM的发现将是引力在很小程度上违反宇称和时间反演对称性的证据，也是广义相对论基础的等效原理的崩溃。这个实验也将为引力场的假设标量和矢量分量设定新的实验极限，并为某些类无质量或几乎无质量的类轴子赝标量粒子的存在设定新的极限。这项新的实验研究的动机是最近开发的技术在原子磁力学领域，使原子自旋进动的灵敏度显着提高。该实验将利用近共振激光的非线性光学旋转来测量磁场存在下碱金属原子的自旋进动频率，并利用两个不同基态超精细能级的频率差异来寻找只与异常相互作用成比例的信号。这项工作将通过测试引力对宇称和时间的尊重程度，从根本上推进我们对引力的认识。反转对称性，并通过探测等效原理的极限。在理论层面上，我们正在做出巨大的努力，将我们对引力的理解整合到量子场论的框架中，这项工作提供了一个独特的机会，可以获得对引力对称性的新的实验见解。此外，还将开发用于精确测量自旋极化原子进动的新技术，推动下一代超灵敏原子磁力计和陀螺仪的技术发展。该研究项目为加州州立大学东湾分校的实验物理实践教学提供了综合方法的基础。将开发高级实验室课程的新课程，以提供与正在进行的研究的自然联系，本科生将直接参与研究计划。在这个机构的一个积极的研究计划将特别有利于多样化的学生群体，因为我们的学生的三分之二是女性和超过百分之七十是代表性不足的少数民族。

This award supports an experiment to search for a new long-range coupling between nuclear spins and the mass of the Earth. Depending on interpretation, the experiment would improve present experimental limits by as much as two orders of magnitude or more. The presence of such an interaction would imply the existence of a gravitational dipole moment (GDM) of an elementary particle --- which can be envisioned semiclassically as a small separation between the position of the center of inertial mass and the center of gravitational mass. Detection of a GDM would be evidence that gravity violated parity and time-reversal symmetries to a small degree, as well as being a breakdown of the equivalence principle which underlies the theory of general relativity. The experiment would also set new experimental limits on hypothetical scalar and vector components of gravitational fields, and new limits on the existence of certain classes of massless or nearly massless axion-like pseudoscalar particles. This new experimental search is motivated by recently developed techniques in the field of atomic magnetometry enabling significant improvement in sensitivity to atomic spin precession. The experiment will use nonlinear optical rotation of near-resonant laser light to measure the spin-precession frequency of alkali atoms in the presence of a magnetic field and use differences between the frequencies for the two different ground state hyperfine levels to search for a signal proportional only to anomalous interactions.This work will fundamentally advance our knowledge of the gravitational force by testing how well gravity respects parity and time-reversal symmetries, and by probing the limits of the equivalence principle. Tremendous efforts at the theoretical level are being undertaken to integrate our understanding of gravity into the framework of quantum field theory, and this work offers a unique opportunity to gain new experimental insight into the symmetry properties of gravity. Furthermore, new techniques for precision measurement of the precession of spin-polarized atoms will be developed, advancing the technology driving the next generation of ultra-sensitive atomic magnetometers and gyroscopes.This research program forms the basis for an integrative approach to hands- on education in experimental physics at California State University, East Bay. New curricula for the advanced laboratory course will be developed to provide a natural connection to the ongoing research, and undergraduate students will be directly involved in the research program. An active research program at this institution will especially benefit a diverse student population, since two-thirds of our students are women and over seventy percent are underrepresented minorities.