# The 27th International Conference on Atomic Physics

17-22 July 2022
Royal Conservatory of Music, Toronto
America/Toronto timezone

## Measurements of $n$p - 2s transitions in the hydrogen atom

21 Jul 2022, 17:00
1h 30m
Hart House (Hart House)

### Hart House

#### Hart House

7 Hart House Cir, Toronto, ON M5S 3H3
Poster presentation Precision measurement and tests of fundamental physics

### Description

Precision experiments in the hydrogen atom have a long tradition and extensive studies of transitions between low lying $n\leq12$ states were carried out [1-6]. These measurements can be used to determine values of the Rydberg constant and the proton charge radius. We present a new experimental approach to perform measurements of transition frequencies between the metastable 2s $^{2}$S$_{1/2} (F = 0,1)$ state of H and highly excited $n$p-Rydberg states with principal quantum number $n \geq 23$.
We generate the hydrogen atoms by dissociating H$_2$ in a dielectric barrier discharge located at the orifice of a pulsed cryogenic valve. The hydrogen atoms are entrained in the supersonic expansion of H$_2$. The atoms are photoexcited to a specific hyperfine level of the metastable 2s $^{2}$S$_{1/2}$ state by a home-built frequency-tripled Fourier-transform-limited pulsed titanium-sapphire laser (pulse length 40 ns). They enter a magnetically shielded region in which transitions to $n$p Rydberg states are induced by a narrow-band frequency-doubled continuous-wave titanium-sapphire laser, which is phase locked to an optically stabilized frequency comb and referenced over a fiber network to a SI traceable primary frequency standard [7]. The highly excited Rydberg states are detected by pulsed-field ionization. We will report progress on our efforts to minimize uncertainties from stray electric fields and Doppler shifts and to obtain spectral lines with a FWHM below 10 MHz.
This work was supported by the Swiss National Science Foundation through the Sinergia-Program (Grant No. CRSII5-183579) and Grant No. 200020B-200478.

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[3] A. Beyer $\textit{et al.}$, Science $\textbf{358}$, 79 (2017).
[4] H. Fleurbaey $\textit{et al.}$, Phys. Rev. Lett. $\textbf{120}$, 183001 (2018).
[5] N. Bezginov $\textit{et al.}$, Science $\textbf{365}$, 1007 (2019).
[6] A. Grinin $\textit{et al.}$, Science $\textbf{370}$, 1061 (2020).
[7] D. Husmann $\textit{et al.}$, Optics Express $\textbf{29}$,24592 (2021).

Presenter name Simon Scheidegger

### Primary authors

Simon Scheidegger (ETH Zurich) Mr Joseph Anton Agner (ETH Zurich) Mr Hansjürg Schmutz (ETH Zurich) Prof. Frédéric Merkt (ETH Zurich)

### Presentation Materials

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