Speaker
Description
The long lifetimes of highly excited Rydberg states make them very attractive for precision experiments. Until now, these states were disregarded in precision spectroscopic studies of the hydrogen atom, mainly because of their large dc-polarizabilities at nominal zero electric field strength, which result in uncontrollable systematic frequency shifts. Recently, we demonstrated how to circumvent the unwanted influence of the dc-Stark effect in high Rydberg states (principal quantum number $n\geq$20) by measuring individual Rydberg-Stark states ($k = 0, \pm2$) and using the line positions to correct for the perturbation induced by the electric fields [1].
This approach will be illustrated by measurements of the $n=24 \leftarrow 2\,^2\mathrm{S}_{1/2}(f=1)$ and $n=20 \leftarrow 2\,^2\mathrm{S}_{1/2}(f=0,1)$ transition frequencies [2]. The results are used to determine the ionization energy of H with unprecedented accuracy. In combination with the Lamb-shift measurement from Bezginov et al. [3] we derive a value of the Rydberg constant that is independent of the exact value of the proton charge radius [2].
This work is supported by the Swiss National Science Foundation through the Sinergia-Program (Grant No. CRSII5-183579) and Grant No. 200020B-200478.
[1] S. Scheidegger et al., Phys. Rev. A 108, 042803 (2023).
[2] S. Scheidegger and F. Merkt, Phys. Rev. Lett. (in press).
[3] N. Bezginov et al., Science 365, 1007 (2019).
