Speaker
Description
The energy levels of hydrogen-like systems can be both calculated and measured very precisely. Precision spectroscopy of two transitions at the current level of accuracy allows the determination of the Rydberg constant and the proton charge radius. Comparison with additional transitions can serve as a consistency check for the theory of quantum electrodynamics. Improvements in these measurements in the last years, revealed small discrepancies, which are not yet fully resolved.
I will present the latest measurement of the 1S-3S transition in hydrogen, using two photon direct frequency comb spectroscopy and explain the experimental technique along with our setup. The obtained result ( f1S−3S = 2,922,743,278,665.79(72) kHz) supports the value of the proton charge radius, first obtained from muonic hydrogen. The value differs by 2.1 standard deviations from the recent measurement of the same transition obtained at Laboratoire Kastler Brossel suggesting, that the discrepancies in these precision measurements probably arise due to yet unknown experimental issues. Therefore, we hope that further investigation of the experiments will resolve this deviation. I will give an update on the status of the experiment, the next intermediate results and the anticipated improvements for the next measurement campaign.
