Cavity-atom interactions in a thermal strontium beam Development of a simple apparatus for quantum metrology

This thesis presents research conducted at the University of Amsterdam under the supervision of Prof. Dr. Florian Schreck and Dr. Stefan A. Schäfer, focused on developing a superradiant clock based on the kilohertz transition of strontium-88. To date, this experimental apparatus remains the only one of its kind.
Although continuous superradiance has not yet been achieved, significant experimental progress has been made. Key technical challenges were identified and addressed through successive upgrades to the apparatus. Chapter 3 details these modifications, while Chapter 6 introduces a novel method for transverse cooling of the high-density atomic beam, which was successfully implemented.
Following these experimental improvements, light amplification resulting from the collective emission of atoms in the 3P₁ lasing state was observed, with gains reaching up to 500%, a fortyfold improvement over previously reported values. These results are presented in Chapter 7. Additionally, Chapter presents the first observation of the onset of collective emission from the atomic ensemble, marking a critical milestone toward achieving sustained superradiant emission.
This work represents a substantial step toward realizing a continuous superradiant laser. While the final goal has not yet been attained, the methods developed and the results obtained lay a strong foundation for future advances. The continued refinement of this experimental platform is expected to enable the full realization of continuous superradiance, with significant implications for precision metrology and fundamental atomic physics.