ED Sciences Physiques et de l'Ingénieur
Emergent physics with cold atoms in a hollow core fiber
by Luisa LORANCA CRUZ (Laboratoire Photonique, Numérique & Nanosciences)
The defense will take place at 14h00 - Amphithéâtre Rue François Mitterrand, 33400 Talence
in front of the jury composed of
- Andrea BERTOLDI - Ingénieur de recherche - Université de Bordeaux - Directeur de these
- Marco PREVEDELLI - Professeur - Department of Physics and Astronomy - Rapporteur
- Tim FREEGARDE - Professor - University of Southampton - Rapporteur
- Juliette BILLY - Maîtresse de conférences - LCAR - Examinateur
- Helmut RITSCH - Professeur - University of Innsbruck - Examinateur
- Philippe TAMARAT - Professeur - LP2N - Examinateur
Cold atoms are versatile quantum systems that enable the study of numerous quantum phenomena through precise tools and a high degree of control. Many experiments use these systems to explore spontaneous organization phenomena: systems that are initially disordered undergoing a phase transition to an ordered state due to interactions between their constituents. Most studies in this field rely on atoms confined in cavities. However, such cavities impose the light modes interacting with the atoms by their boundary conditions, thereby predetermining the final geometry the system. Some experiments using ring cavities, which lack standing waves, offer an additional degree of freedom. In our experiment, we aim to go even further: the experiment we developed and describe in this thesis aims to induce the spontaneous crystallization of cold atoms in free space. By confining atoms in a hollow-core fiber (HCF), we focus on one dimension, considering the atoms to be in free space along the longitudinal direction of the fiber. The cold atom crystal would be formed by long-range interactions induced by the light interacting with the atoms, simultaneously generating a light crystal that did not initially exist. Beyond a certain intensity threshold, these interactions would break the translational symmetry of the atomic cloud, with a spacing determined only by the characteristics of the cloud and the light, rather than by a standing wave. This type of experiment could contribute to the study of long-range interactions, the mechanisms of crystal formation, and could find applications in quantum simulations or magnetic field sensors. Finally, an important aspect is that the size of cold atom experiments generally remains too large to enable measurements outside vacuum chambers. In the case of atomic sensors, the measured forces often depend on the inverse of the distance from the observed fields. It is therefore crucial to work towards the miniaturization of cold atom experiments. Although other studies exploit HCFs, this experiment is unique in that it connects two vacuum chambers via an HCF, with the goal of using cold atoms as magnetic field sensors between the chambers. This represents a step towards more compact devices for cold atom experiments. This project began with my doctoral research therefore, in this thesis, I present the development and construction of this new experiment, as well as the initial results concerning the cold atom source, the loading of atoms into the HCF, and a brief introduction to spontaneous organization phenomena.