Continuous Strong Coupling of Cold Atoms to an Optical Microcavity and Heralded Single‐Photon Emission

Neutral atoms coupled to optical microcavities provide an efficient atom‐photon interface for quantum computing, quantum networking and quantum metrology. However, the finite trapping lifetime of atoms generally requires cyclic atom transfer, which interrupts the atom‐cavity interaction and limits the applications of cavity QED experiments. Here, we realize continuous coupling of rubidium atoms to an optical microcavity. Continuous transfer of atoms from a magneto‐optical trap into the optical microcavity is achieved using a near‐resonant optical dipole trap, enabling strong coupling between an atomic ensemble and the microcavity with a vacuum Rabi splitting of 395(2) MHz. To demonstrate a potential application, we further realize continuous heralded single‐photon emission and measure a minimum value of the heralded second‐order correlation function, . These results pave the way for the continuous transfer of atoms into optical microcavities and broaden the application prospects of laser‐cooled atoms coupled to optical microcavities.