Cold molecule synthesis on a nanophotonic microring circuit

Cold molecules can be synthesized from a pair of cold atoms via photoassociation (PA) followed by spontaneous decay. However, the decay channel is not unique due to complex rovibration energy levels. Through enhancing the radiative coupling between an excited state and a targeted ground state, it is possible to synthesize a cold ground state molecule with near-unity efficiency. Our goal is to achieve strong coupling between a single Rb atom and subsequently a Rb₂ excited state molecule with a whispering gallery mode nanophotonic resonator. We aim at achieving large molecule-photon cooperativity that can enhance the decay rate towards a rovibrational ground state. Our experiment will make use of optical tweezers to localize Rb atoms on a high-Q Si₃N₄ microring resonator, followed by performing resonator-enhanced PA of ground state molecules. We will discuss our experiment setup, and a state-sensitive optical detection scheme that may be realized to achieve near-unity quantum state detection fidelity.