Real-Time Observation of Single Atoms Trapped and Interfaced to a Nanofiber Cavity

We demonstrate efficient interfacing of individually trapped single atoms to a nanofiber cavity. The cavity is formed by fabricating photonic crystal structures directly on the nanofiber using femtosecond laser ablation. The single atoms are interfaced to the nanofiber cavity using an optical tweezer based side-illumination trapping scheme. We show that the fluorescence of individual single atoms trapped on the nanofiber cavity can be readily observed in real-time through the fiber guided modes. From the photon statistics measured for different cavity decay rates, the effective coupling rate of the atom-cavity interface is estimated to be 34±2  MHz. This yields a cooperativity of 5.4±0.6 (Purcell factor=6.4±0.6) and a cavity enhanced channeling efficiency as high as 85±2% for a cavity mode with a finesse of 140. The trap lifetime is measured to be 52±5  ms. These results may open new possibilities for deterministic preparation of single atom events for quantum photonics applications on an all-fiber platform.