Ultracold Strontium Atoms Interacting with a 'Bad' Ring Cavity: Inertial Sensing with Matter Waves and Collective Bistability

Charlista: Prof. Philippe Courteille, Instituto de Física de São Carlos, Universidade de São Paulo

Resumen: This seminar is dedicated to light-matter interaction shaped by the presence of an optical ring cavity with applications in quantum sensing. We constructed an experiment to cool down clouds of strontium atoms to temperatures close to the single photon recoil limit and store them in the dipolar potential formed by a mode of the ring cavity. Driving the cavity near the 7.5kHz narrow intercombination transition, 0.1 photons are enough to saturate the atoms, which enables us to study for the first time saturation-induced non-linear bistability on resonance without being hampered by spontaneous emission. With the cavity decay rate exceeding by far the rate of spontaneous emission, we are in the so-called 'bad cavity' limit. The number of interacting atoms is sufficiently high to reach the strong collective coupling regime characterized by normal mode splitting of the cavity transmission spectrum. Currently, we are setting up a high sensitivity matter-wave interferometer for inertial sensing and gravimetry. It is based on observing 'in vivo' Bloch oscillations performed by the atoms inside a periodic optical lattice formed by two counter-propagating modes of the ring cavity and exploits the fact that the periodicity of the oscillations is strictly proportional to external forces.