Ultrahigh-Sensitivity Search for an Electric Dipole Moment of^<129>Xe atom by Means of Nuclear Spin Maser with Artificial Feedback

在中性K衰变中知道CP不变性已经有40多年了，最近在B衰变中也证实了这一点，它仍然是当代粒子物理学的重要课题之一。标准模型(SM)在K-M矩阵元素中以复相的形式包含CP破坏，并很好地描述了观测到的风味变化的K和B衰变，但从未提供可检测大小的永久电偶极矩(EDM)。另一方面，超对称模型等超对称模型预测了EDM的巨大价值，从而使EDM成为SM之外的物理探测器。本研究旨在发展一种能够精确测量自旋进动频率的新的核自旋激射器方案，从而为超高灵敏度寻找电火花加工铺平道路。在直径22 mm的玻璃盒中，用光泵Rb蒸气进行自旋交换，成功地极化了直径为22 mm的玻璃盒中的Xe气体的自旋自旋，用激光探测到了它们的进动，并首次通过人工反馈观察到了自持进动。频率精度随测量时间T的变化规律为Δv∝1/T^&1.5&gt；直到T=30 0 0 S，然后趋于平坦化。根据这一结果，我们对装置进行了几项改进，包括磁屏蔽、磁流稳定、激光操作和波长稳定以及电池温度控制，最终在测量时间T=30000 S的情况下达到了Δv=9.3nHz(相当于Δd~9×10^&lt；-28&gt；ecm)。同时，发现了一些对v精度有决定性影响的问题，绝对值得进一步改进。因此，我们得出结论，本工作证实了原子电火花加工搜索新方法的有效性，并明确了实现期待已久的电火花加工精度的方向。

Violation of CP invariance, known for more than 40 years in neutral K decay and recently confirmed also in B decay, remains one of vital subjects in contemporary particle physics. The standard Model (SM) includes the CP violation in a form of complex phase in the K-M matrix elements and well represents the observed flavor-changing K and B decays, but never provide a permanent electric dipole moment (EDM) of detectable size. On the other hand, models proposed beyond the SM, such as supersymmetric one, predict sizeable values for EDM, thus rendering EDM an exclusive position as a probe of physics beyond the SM. The present research has aimed at development of new scheme of nuclear spin maser that enables precision determination of spin precession frequency, in order to pave a route for ultrahigh-sensitivity search for an EDM in a ^<129>Xe atom.^<129>Xe nuclear spins of Xe gas contained in a 22 mm-diameter glass cell were successfully polarized by spin exchange with optically pumped Rb vapor, their precession was detected by probe Laser light, and a self-sustaining precession by means of an artificial feedback was observed for the first time. The observed precision in frequency proved to improve as Δv ∝ 1/T^<1.5> as a function of the measurement time T until T = 3000 s, and then tended to be flattened. Following this result, we worked out several improvements in the setup, including the magnetic shielding, magnet current stabilization, Laser operation and wavelength stabilization, and cell temperature control, and finally attained Δv = 9.3 nHz (amounting to EDM sensitivity of Δd 〜 9×10^<-28> ecm) in a measurement time T = 30000 s. Also, a number of issues were identified that have decisive effects on the v precision and definitely deserve further work for improvement. We thus conclude that the present work has confirmed effectiveness of novel method for the atomic EDM search, and has clarified the directions that should enable the long awaited EDM precision.