Entangled ions in an optical cavity

"Optical cavities provide a coherent interface between light and matter that can be used to link remote quantum systems. With such an interface, quantum information can be mapped from a single atom onto a photon for long-distance transport, and an atom can be entangled with a cavity photon as a resource for teleportation. However, in a future quantum network, it would be advantageous for each cavity to contain multiple atoms. These atoms could be used for local quantum information processing, error correction between network nodes, and improved quantum memories, among other tasks.I will describe the coupling of two calcium ions to the mode of a high-finesse optical cavity. When both ions are coupled with near-maximum strength to the cavity, we entangle the ions with one another, heralded by the measurement of two orthogonally polarized photons. Applications of entangled ions in a cavity will be discussed, in the context of both quantum information tasks and the investigation of open quantum systems. In particular, I will present recent measurements of enhanced quantum state transfer from a superradiant two-ion state."