Precision one-photon spectroscopy of the 2S-nP states in atomic hydrogen

德国-俄罗斯联合项目的目标是氢原子2S-6P和2S-9 P单光子跃迁的精确光谱学，目标绝对频率不确定性为1 kHz。该项目延续了我们之前的研究，我们引入了2S-4P光谱的原始方法，并达到了2 kHz的不确定度。在本项目中，将实施一些新的方法来减少由于多普勒效应、量子干涉效应和DC斯塔克位移引起的不确定性，这些不确定性是当前2S-4P数据的主要系统不确定性。在亚稳态氢原子冷束上410 nm处的2S-6P跃迁光谱提供了进一步减少领先系统贡献的可能性，这是由于更窄的自然线宽和对量子干涉位移的更低灵敏度。2S-9 P跃迁的光谱学提供了对相互作用区域中的电杂散场的灵敏测量，并完成了对氢原子单光子跃迁的精确频率测量。该项目的结果将对解决质子尺寸难题具有决定性意义，并将成为量子电动力学最精确的测试之一。结合μ介子氢和1 S-2S跃迁频率测量的实验，它将在下一次CODATA调整中为我们提供一个改进的和一致的里德伯常数值。

The Joint German-Russian project aims for precision spectroscopy of the 2S-6P and 2S-9P one-photon transitions in atomic hydrogen with the target absolute frequency uncertainty of 1 kHz. The project continues our previous research where we introduced the original method for 2S-4P spectroscopy and reached an uncertainty of 2 kHz. A number of new approaches will be implemented in this project to reduce the uncertainty due to the Doppler effect, quantum interference effect and DC Stark shift, being the leadingsystematic uncertainties of the current 2S-4P data. Spectroscopy of the 2S-6P transition at 410 nm on a cold beam of metastable hydrogen atoms offers possibilities to further reduce leading systematic contributionsdue to narrower natural line width and lower sensitivity to quantum interference shifts. Spectroscopy of 2S-9P transition offers a sensitive measurement of electric stray fields in the interaction region andcompletes the set of precision frequency measurements of one-photon transitions in atomic hydrogen.Results of the project will be decisive for resolving the proton size puzzle and will be one of the most accurate tests of quantum electrodynamics. Together with experiments in muonic hydrogen and 1S-2S transition frequency measurements, it will give us an improved and consistent value of the Rydberg constant in the next CODATA adjustment.