Interfacing of an Optical Nanofiber with Tunably Spaced Atoms in an Optical Lattice

Abstract: We experimentally demonstrate efficient interfacing of a large number of atoms to an optical nanofiber using an optical lattice with tunable spacing ($0.88-1.5~\mu$m) [1] projected onto the nanofiber. The lattice beam and reflections from the nanofiber yield trap potentials that provide tight confinement in all motional degrees of freedom $\approx 220$ nm above the nanofiber surface, enabling efficient atom-photon coupling. We achieved trapping of $\approx1300$ atoms in periodic trap sites with a trap lifetime of $\approx15$ ms. We also observe the effect of varied lattice period on the atomic motional frequencies. Our new scheme is adaptable to other nanophotonic cold-atom systems and provides a versatile and scalable platform for studying photon-mediated long-range collective interactions. Our tunable lattice-nanofiber system could be seamlessly integrated with optical tweezers, allowing both the scalable atom-photon interface and individual single-atom access, and its intrinsic connectivity to conventional fiber provides a significant advantage towards quantum networks.