Atom-light Interaction with Trapped Cold Atoms on an Integrated Nanophotonic Circuit

Achieving strong interaction between single atoms and single photons, especially in the optical frequency domain, is a challenging and long-standing goal in quantum optics and quantum information science. The integration of cold atoms with nanophotonic devices has recently enabled the development of new experimental tools for enhancing light-matter interactions in cavity and waveguide quantum electrodynamics (QED) settings. Advances in nanophotonic engineering, combined with the cooling and trapping of single atoms into arrays near nanoscale dielectrics, are opening up new opportunities for realizing scalable and efficient atom-light interactions. However, the control and manipulation of the cold atoms near nanophotonic structures on a planar surface are still challenging and remain elusive.

In this thesis, we present the first successful realization of trapping cold neutral atoms on a microring resonator within an integrated nanophotonic circuit. We observed strong coupling of single atoms to a whispering-gallery-mode (WGM) resonator via an optical guiding method, enabling chiral atom-photon coupling and the routing of non-classical on-chip photons by single atoms. Following the optical guiding, we demonstrate the cooling and trapping of a dense ensemble of cesium atoms into an optical microtrap above the microring resonator using the degenerate Raman-sideband cooling (dRSC) method. The trapped atoms exhibit strong cooperative coupling and superradiant decay into a WGM. In addition to these techniques, we also explore other experimental methods, such as the optical conveyor belt technique. By preparing an atomic ensemble with high density near a nanophotonic microring resonator, we study collective emission into both guided and non-guided modes, demonstrating the first selective collective emission behaviors in our system. Our experimental realization and demonstration could enable the study of novel collective behaviors of atomic excitations and facilitate applications of trapped atoms on nanophotonic circuits in quantum optics and many-body physics.