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

• Applicant: Professor Dr. Theodor W. Hänsch
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 319911867

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.

• DFG Programme: Research Grants
• International Connection: Russia
• Partner Organisation: Russian Foundation for Basic Research
• Cooperation Partners: Dr. Ksenia Khabarova; Nikolai Kolachevsky, Ph.D.; Ilya Semerikov; Ilya Zalivako