Soutenance de thèse de Sara PANCALDI

Soutenance de thèse de Sara PANCALDI, doctorante dans le groupe Optique quantique du Laboratoire Charles Fabry, le 17 décembre 2025 à 14h00 dans l'Auditorium de l'Institut d'optique graduate school à Palaiseau, sur le thème : "Building a new flexible set-up for the measurement of collective light-matter effects in a dense atomic cloud."

Résumé : "This thesis describes the construction, the characterization and the bench-marking of an experimental set-up which provides a cold-atom based platform to study light-matter interactions. The set-up is based on very compact vacuum design, including a glass cell as science chamber. The goal of the set-up is to trap high atom numbers, in the range of thousands, in a very small dipole trap, referred to as “optical tweezers”. Atom-light interactions are well understood in the case of an ensemble of two-level emitters independently coupled to the light field, but on this set-up the atomic cloud reaches such high densities that dipolar coupling among the emitters play a significant role. This platform provides means to study the effect on the emitted atomic fluorescence of this collective interaction between the atoms and the light field. The fundamental interest is to explore and characterize regimes where both the numerical and the approximated pictures fail to predict the observables of the system, despite the knowledge of the microscopic dynamics. The thesis gives an introduction to the theoretical interest and motivation for the investigation of such effects and the construction of this set-up and the practical advantages of building this set-up as an upgrade of a similar older experiment to enhance its performances. The thesis also details the first measurements of the collective light-matter effects on this new set-up."