Precision measurements in one- and two- electron atoms for determinations of fundamental constants and tests of symmetries

测量原子氢的兰姆位移以确定质子的电荷半径： 我们将使用分离振荡场（SOF）的拉姆齐技术测量氢原子中的2S到2 P间隔，精确度为2 kHz，改进了1980年Lundeen和Pipkin的测量。我们的测量，沿着与现有的高精度QED理论，将导致0.6%的质子电荷半径的测定，揭示了4.3%（7西格玛）之间的差异，使用μ子氢和氢光谱和电子-质子散射得到的质子半径。 测量氦原子的精细结构以确定精细结构常数： 我们用SOF（PRA 79，060503）对氦原子的n=2三重态P精细结构进行了亚自然线宽微波测量。我们现在已经设计了一种检测方案，该方案涉及通过将这些原子共振转移到先前空的亚稳n=2三重态S子能级来直接检测n= 2三重态P原子，这允许更高的检测效率和更低的背景，并且消除了我们测量中最大的系统效应。我们希望将我们的350 Hz精度提高到优于30 Hz，这将提供一个重要的QED测试，并导致0.5 part-per-billion的精细结构常数的测定。此外，我们已经确定了一个以前被忽视的系统效应，由于量子力学干涉从遥远的相邻共振，这是重要的测量这些间隔和大范围的其他精密测量。 被俘获反氢的精确光谱学：CPT对称性和反物质物理学的检验： 我们在约克的团队继续积极参与ATRAP（哈佛大学、美因茨大学、Julich大学和约克大学之间的合作，由G. Gabrielse）。ATRAP现在已经成功地实现了三个目标中的两个：冷反氢的产生（PRL 89，213401）和在Ioffe阱中捕获这些原子（PRL 108，113002）。第三个目标是对这些原子进行精确的光谱分析。

Measurement of the Lamb shift in atomic hydrogen to determine the charge radius of the proton: We will measure the 2S-to-2P intervals in atomic hydrogen to an accuracy of 2 kHz using the Ramsey technique of separated oscillatory fields (SOF), improving on the 1980 measurement of Lundeen and Pipkin. Our measurements, along with existing highly-precise QED theory, will each lead to a 0.6% determination of the proton charge radius, shedding light on the 4.3% (7 sigma) discrepancy between a proton radius obtained using muonic hydrogen and one from hydrogen spectroscopy and electron-proton scattering. Measurement of the fine-structure of atomic helium to determine the fine-structure constant: We have performed subnatural linewidth microwave measurements of the n=2 triplet P fine structure of helium using SOF (PRA 79, 060503). We have now devised a detection scheme that involves direct detection of the n=2 triplet P atoms by resonant transfer of these atoms to a previously emptied metastable n=2 triplet S sublevel, which allows for higher detection efficiency and lower background, and which removes the largest systematic effect in our measurement. We expect to improve our 350-Hz accuracy to better than 30 Hz, which will provide an important test of QED and lead to a 0.5 part-per-billion determination of the fine-structure constant. Additionally, we have identified a previously overlooked systematic effect due to quantum mechanical interference from distant neighboring resonances that is important for measurements of these intervals and for a large range of other precision measurements. Precise spectroscopy of trapped antihydrogen: a test of CPT symmetry and of antimatter physics: Our group at York continues an active participation in the ATRAP (a collaboration between Harvard, Mainz, Julich and York led by G. Gabrielse). ATRAP has now been successful in 2 of its 3 goals: production of cold antihydrogen (PRL 89, 213401) and trapping of these atoms in a Ioffe trap (PRL 108, 113002). The third goal of performing precise spectroscopy on these atoms remains.