Collective interactions between light and ultracold atoms

• Grant number: 25/20246-1
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: December 01, 2025
• End date: November 30, 2026
• Field of knowledge: Physical Sciences and Mathematics - Physics - Atomic and Molecular Physics
• Principal Investigator: Philippe Wilhelm Courteille
• Grantee: Gustavo Henrique de França
• Supervisor: Sebastian Slama
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Institution abroad: Eberhard Karls Universität Tübingen, Germany
• Associated to the scholarship: 23/10014-0 - Collective atom-light interaction, bistability and quantum correlations mediated by an optical cavity, BP.DD

Abstract

Quantum-correlated systems lie at the core of modern quantum information technologies. For quantum sensing applications, cold atomic ensembles represent an ideal platform, where strong correlations can be engineered through their interaction with a single light mode stored in an optical cavity. In recent years, the group led by Prof. Ph. Courteille at the Instituto de Física de São Carlos has developed an experimental platform in which ultracold strontium atoms are resonantly driven on a narrow optical transition and coupled to the counter-propagating modes of a laser-pumped optical ring cavity. A major milestone has been the first observation of bistable behavior in the quantum regime dominated by atomic saturation, opening new perspectives for the realization of weakly entangled, spin-squeezed states aimed at improved quantum sensing.In parallel, the group led by Prof. S. Slama at the University of Tübingen has established a complementary experimental platform to study collective interactions among rubidium Rydberg atoms, mediated both by an optical cavity and by Rydberg blockade mechanisms. This system realizes a combined Dicke-Ising spin model, where the interplay between cavity-mediated and long-range interactions is expected to give rise to novel quantum phases of interest for advanced quantum simulators.Despite the differences between both setups - distinct atomic species with very different properties - they rely on similar experimental techniques and address closely related scientific questions. This complementarity makes the cooperation between the two groups particularly valuable: while the São Carlos platform focuses on quantum sensing applications based on superradiance and spin squeezing, the Tübingen setup explores collective phases emerging from the interplay of cavity and Rydberg interactions. Together, these approaches provide the scholarship holder with a unique opportunity to develop a comprehensive understanding of correlated atomic ensembles across different regimes, mastering shared technologies such as laser stabilization, cavity design, and atom-light coupling. This synergy will not only broaden the student's expertise but also strengthen the collaborative bridge between the groups.