Speaker
Description
Precision spectroscopy of atomic hydrogen provides a uniquely clean test of bound-state quantum electrodynamics due to its simple electronic structure. While spectroscopy of trapped atomic samples can significantly enhance precision, trapping hydrogen in optical potentials has not been realized yet. Existing approaches rely on magnetic trapping, which introduce substantial Zeeman shifts and limit spectroscopic accuracy. Furthermore standard laser-cooling techniques are difficult to apply to atomic hydrogen due to its small mass as well as the comparatively large transition energies involving the ground state. We pursue an alternative approach based on recoil-assisted loading into an optical dipole trap. In combination with the magic wavelength near 515 nm for the 1S–2S transition, this enables Doppler-free spectroscopy without requiring ultracold temperatures, opening the pathway towards precision measurements in an optically trapped hydrogen system. At the Max Planck Institute of Quantum Optics, we currently develop the experimental infrastructure enabling controlled interrogation of the 1S–2S two-photon transition at 243 nm. We further analyze relevant systematic effects, including residual Doppler contributions, Zeeman shifts, and intensity-dependent perturbations, outline strategies for their control within the current setup and give an estimation on their contribution. These developments establish the experimental foundation for precision spectroscopy of optically trapped hydrogen and represent a step towards a computable atomic clock, directly linked to fundamental constants such as the Rydberg constant, with potential implications for future redefinitions of the SI second or search for new physics beyond the Standard Model [1,2].
- O. Amit, D. Taray, V. Wirthl, V. Weis, M. W. Syed, A. Ozawa, J. Weitenberg, S. G.
Karshenboim, J. T. M.Walraven et al., Towards trapping of hydrogen atoms for computable optical clock applications, DOI: 10.1103/3bnr-q23f, 2025. - E. Tiesinga, P. J. Mohr, D. B. Newell, and B. N. Taylor, CODATA recommended values of the fundamental physical constants: 2018, Rev. Mod. Phys. 93, 025010 (2021).