Probing atom-surface interactions with an atomic quantum sensor

This thesis presents the first force measurements at close range between an atom and a surface, which was the ultimate objective of the Forca-G project.

The force is measured by atom interferometry with atoms trapped in potential wells formed by a vertical optical lattice. Stimulated Raman transitions are used to measure the energy difference between two wells, i.e. the force applied to the atoms. By moving the atoms to different distances from the mirror in a controlled manner using a Bloch lift, it is possible to measure variations in surface forces with a spatial resolution of the order of a micrometre. In the vicinity of the surface, a force measurement sensitivity of 3.4×10^-28 N has been achieved, which is state-of-the-art for surface force measurements. At atom-surface distances of less than a hundred micrometres, electrostatic forces dominate, due to the electrostatic fields generated by atoms adsorbed on the surface. By modelling these fields, another force is highlighted: the Casimir-Polder force. These parasitic electric fields have been measured directly with the trapped atoms, making it possible to correct, albeit imperfectly, the measurements of the impact of the electrostatic forces.

Finally, we have shown that the amplitude and the orientation of the atom-surface forces are modified by the illumination of the surface with UV light, which charges the surface.

quantum, interferometry, cold atoms, Casimir-Polder, trapped atoms

Full document (FR) : TEL-04680406