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

CP不变性的破坏在中性K衰变中已经存在了40多年，最近在B衰变中也得到了证实，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矩阵元中以复相位的形式包含CP破坏，很好地代表了所观察到的变味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，超越SM提出的模型，如超对称的，预测相当大的价值EDM，从而使EDM的一个独特的位置，作为一个探针的物理超越SM。本研究的目的是发展一种新的核自旋脉塞方案，使自旋进动频率的精确测定成为可能，为超高灵敏度地寻找原子中的EDM铺平道路<129>。<129>在直径为22 mm的玻璃池中，用光泵Rb蒸气进行自旋交换，成功地极化了氘气的氘核自旋，用探测激光探测了它们的旋进，并首次观察到人工反馈的自持旋进。在T = 3000 s之前，观测到的频率精度被证明作为测量时间T的函数以Δv 1/T^的形式提高<1.5>，然后趋于平坦。在此基础上，对装置进行了磁屏蔽、稳流、稳频、稳频和控温等改进，在30000 s的测量时间内，获得了Δv = 9.3 nHz（相当于EDM灵敏度Δd = 9×10^<-28>ecm）。此外，还发现了一些对v精度有决定性影响的问题，这些问题肯定值得进一步改进。因此，我们的结论是，目前的工作已经证实了新方法的有效性，原子EDM搜索，并澄清了方向，应该使期待已久的EDM精度。

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.