High Quality factor micro-ring resonator for strong atom-light interactions using miniature atomic beams

Abstract: An integrated photonic platform is proposed for strong interactions between atomic beams and annealing-free high-quality-factor (Q) microresonators. We fabricated a thin-film, air-clad SiN microresonator with a loaded Q of $1.55\times10^6$ around the optical transition of $^{87}$Rb at $~780$ nm. This Q is achieved without annealing the devices at high temperatures, enabling future fully integrated platforms containing optoelectronic circuitry as well. The estimated single-photon Rabi frequency (2g) is ${2\boldsymbol{\pi}}\times$64 MHz at a height of 100 nm above the resonator. Our simulation result indicates that miniature atomic beams with a longitudinal speed of 0.2 m/s to 30 m/s will strongly interact with our resonator, allowing for the detection of single-atom transits and the realization of scalable single-atom photonic devices. Racetrack resonators with a similar Q can be used to detect thermal atomic beams with velocities around 300 m/s.