Progress towards the Strong Interaction between Thermal Atoms and Microring Resonator with High-Quality Factor

Quantum sensors based on thermal atoms offer simplicity in comparison to laser cooling and may further have lower vacuum requirements. In this work, we investigate single-atom detectability based on strong coupling of thermal atoms to a micro-ring resonator with a high quality (high-Q) factor. In our experimental platform, we fabricate a silicon nitride (SiN) high-Q microring resonator on an integrated photonic chip with bus waveguides to couple light in and out through the edge. The chip is attached to a thermoelectric cooler (TEC) that is capable of tuning and stabilizing the resonance frequency of the resonator to the D2 optical transition of ⁸⁷Rb at 780 nm. The customized assembly is hosted in a quartz cell under a vacuum level of 10^-6 Torr which is much higher than the pressure used in cold atom systems. The laser beam is coupled in and out of the bus waveguide using long working distance microscope objective in a confocal configuration to achieve high coupling efficiency. We then generate the atomic vapor by inductively heating a welded loop of Rb dispensers. This platform enables the study of the interaction between thermal atoms and SiN resonators in order to investigate atom-light interactions at a miniature scale.