FOMO2022 Invited Talk,  Saïda Guellati-Khélifa

Invited Talk: Determination of the fine-structure constant using atom interferometry

Léo Morel1, Zhibin Yao1, P. Cladé1 and S. Guellati-Khelifa1,2
1Laboratoire Kastler Brossel, Sorbonne University, CNRS, ENS-PSL University, College de France, 4 place Jussieu, 75005 Paris, France
2Conservatoire National des Arts est Métiers, 292 rue Saint Martin, 75003 Paris, France

To test the standard model, we need to know the parameters that scale the fundamental interactions. Among them, the fine structure constant which characterizes the strength of the electromagnetic interaction and thus plays a crucial role in quantum electrodynamics calculations. Using atom interferometry to measure the quotient ħ/mRb of the reduced Planck’s constant and the mass of a rubidium-87 atom, we obtained the most accurate determination of the fine structure constant α=1/137.035999206(11) with a relative accuracy of 81 parts per trillion (ppt) [1]. This value differs by 5.6 σ from the one deduced from the cesium recoil measurement [3].
Combining Ramsey-Bordé interferometer based on Raman diffraction with Bloch oscillations in accelerated optical lattice and using an ultra-stable and robust experimental set-up, we achieved a record sensitivity of 4 x 10-11 to α in 48 h integration time. This enabled us to investigate experimentally several systematic effects, especially those related to wave-front distortions [2].
In this talk, I will present our experiment and I will discuss the impact of the new value of α on the test of the Standard Model based on the comparison between the theoretical and experimental values of the electron anomalous magnetic moment[5, 4]. I will also present some results from our recent work on the atom interferometer based on the diffraction of atoms by a picosecond frequency-comb laser [6].

[1] L. Morel, Z. Yao, P. Cladé and S. Guellati-Khelifa, Nature, 588 (2020), 61–65.
[2] S. Bade et al., Phys. Rev. Lett. 121 (2018), 073603.
[3] R. H. Parker, C. Yu, W. Zhong, B. Estey and H. Müller, Science, 360 (2018), 191–195.
[4] D. Hanneke, S. Fogwell, and G. Gabrielse, Phys. Rev. Lett. 100 (2008), 120801.
[5] T. Aoyama, T. Kinoshita and M. Nio, Phys. Rev. D 97 (2018), 036001.
[6] C. Solaro, C. Debavelaere, P. Cladé, S. Guellati-Khelifa, arXiv:2207.12723.