Phys.org  July 29, 2024 It remains a challenging task to efficiently trap a large ensemble of cold atoms on an integrated nanophotonic circuit. Researchers at Purdue University demonstrated direct loading of an ensemble of up to 70 atoms into an optical microtrap on a nanophotonic microring circuit by employing degenerate Raman-sideband cooling in the microtrap, where a built-in spin-motion coupling arose directly from the vector light shift of the evanescent-field potential on a microring. Atoms were cooled into the trap via optical pumping with a single free space beam. They achieved a trap lifetime approaching 700 ms under continuous cooling. […]