Towards high-rate trapped ion quantum repeaters using fiber-based micromirror cavities

Long-range distributed entanglement over a quantum network has the potential to enhance quantum sensing and improve communication security. Trapped ions are a promising memory qubit for quantum network repeater nodes due to their long coherence times, precise state preparation and control, and high-fidelity two-qubit gates. Current remote ion-ion entanglement rates are limited by collection efficiencies of the mediating photons. Fiber-based optical cavities offer a potential path toward higher rates by supporting a small mode volume and efficient coupling of emitted photons directly into an optical fiber. Having demonstrated compatibility of trapped ions and dielectrics at cryogenic temperatures, we are developing a cryogenic surface-electrode ion trap with an integrated fiber-based micromirror cavity. Here we present on progress towards making high-finesse optical cavities with microfabricated mirrors directly attached and mode-matched into single mode optical fibers as well as fabrication and testing of a trap-integrated flexure structure designed to provide passive cavity alignment and long-term mechanical stability. We also discuss ion transport in the presence of radial optical fibers mimicking the dielectric properties and geometry of an integrated cavity.