Soutenance de thèse de Grégoire PICHARD

Soutenance de thèse de Grégoire PICHARD, doctorant dans le groupe Optique quantique du Laboratoire Charles Fabry, le mercredi 20 mai 2026 à 14h00 dans l'auditorium de l'Institut d'Optique Graduate School à Palaiseau, sur le thème : "Optical tweezers experiment in cryogenic environment for the assembly of large arrays of single atoms".

Résumé : " Individual atoms trapped in optical tweezers constitute a promising platform for quantum simulation and quantum computing. A key challenge is scaling from a few hundred to several thousand controlled atoms. Building an experiment in a cryogenic environment is one possible solution, allowing to considerably extend the lifetime of atoms trapped in optical tweezers and therefore to increase the time available for manipulating them. Another advantage of a cryogenic system is that it increases the coherence time of Rydberg atoms by reducing blackbody radiation, which can introduce unwanted transitions during quantum computation.
During this thesis, we built upon the cryogenic platform previously developed at the Laboratoire Charles Fabry and redesigned the in-vacuum optics in order to integrate microscope objectives, enabling better optical quality across the field for trap generation. We describe the challenges associated with integrating high numerical aperture objectives with a cryogenic system. After a first design iteration enabling the generation of about 2000 traps but with limited and unstable lifetimes, we developed a new optical core combining long lifetimes (~5000 s) and a large number of traps (>2000). Preliminary results obtained in this new system have demonstrated high-fidelity assembly of 1024 individual atoms with defect-free arrays in ~10 % of the experimental runs, using a single moveable optical tweezers. The integration of cryogenics, combined with the development of new assembly techniques, paves the way for major advances in scaling up the neutral-atom platform. "