Abstract Interfacing trapped neutral atoms with light propagating in nanophotonic waveguides enables efficient and long-range photon-mediated atom–atom interactions. Here we demonstrate a hybrid nanophotonic trap for cold neutral atoms, which leverages surface forces for attraction and blue-detuned evanescent light for repulsion. We attribute the attractive potential to a combination of the Casimir–Polder interaction and electrostatic attraction due to charges on the waveguide surface. Despite the shallow depth of the trap, we load atoms into it via adiabatic transfer from a conventional two-colour dipole trap with an efficiency of 96(5)%. Notably, the hybrid trap supports a long atomic storage time of 140(9) ms. Moreover, it exhibits a Ramsey coherence time
T2∗ T 2 * = 17.8(7) ms and spin-echo coherence time
T2′ T 2 ′ = 44.7(2.5) ms, which greatly exceed previously reported values. Our results pave the way for further explorations of atom–surface interactions at the nanoscale and illustrate the potential of harnessing surface forces to enhance storage and coherence times for atoms coupled to nanophotonic waveguides. This advance offers new opportunities for neutral-atom quantum technologies.
Trapped atoms near nanophotonics form an exciting platform for bottom-up synthesis of strongly interacting quantum matter. The ability to induce tunable long-range atom-atom interactions with photons presents an opportunity to explore many-body physics and quantum optics. Here we implement a configurable optical tweezer array over a planar photonic circuit tailored for cold atom integration and control for trapping and high-fidelity imaging of one or more atoms in an array directly on a photonic structure. Using an optical conveyor belt formed by a moving optical lattice within a tweezer potential, we show that single atoms can be transported from a reservoir into close proximity of a photonic interface, potentially allowing for the synthesis of a defect-free atom-nanophotonic hybrid lattice. Our experimental platform can be integrated with generic planar photonic waveguides and resonators, promising a pathway towards on-chip many-body quantum optics and applications in quantum technology.