23th of September 2019 (Paris) – PhD defense of Léo Morel

Léo MOREL will defend his thesis on 23th of September 2019 at 2:00 pm on the subject “High sensitivity matter-wave interferometry: towards a determination of the fine structure constant at the level of 10E-10”, realized at LKB, under the direction of Saïda Guellati-Khelifa and Pierre Cladé.

The defense will take place in the IMPMC conference room (corridor 22/23, 4th floor, room 401), Jussieu campus of Sorbonne Université.

The defense will be in English.


The fine structure constant can be determined from the measurement of the ratio h/m between the Planck constant, h, and the mass of an atom, m. The comparison of the experimental value of the anomalous magnetic moment of the electron or the muon with their theoretical values predicted by the Standard Model using this value of the fine structure constant allows a very precise test of this model.
My thesis work focused principally on the measurement of the h/m ratio of rubidium-87 using a new experimental device. We installed the laser device for atom interferometry, to interrogate a cloud of cold atoms produced by optical molasses. Combining an interferometer using Raman transitions and the Bloch oscillation technique, we demonstrated an unprecedented sensitivity on the measurement of h/m corresponding to a relative statistical uncertainty of 8.5 x 10 -11 in 48 hours of integration, or 4.3 x 10 -11 on the fine structure constant.
This sensitivity has allowed us to experimentally study a variety of systematic effects. We simultaneously carried out modelling work that contributed to the implementation of protocols to compensate for the biases induced by systematic effects. We present a preliminary assessment of the error budget associated with these effects.