Quantum Interference of Photon Pairs emitted from Two Remote Trapped Ytterbium Ions

Peter Maunz,
FOCUS Center and Department of Physics, University of Michigan.

Trapped atomic ions are among the most attractive implementations of quantum bits for applications in quantum information processing, owing to their long trapping lifetimes and long coherence times. While nearby trapped ions can be entangled through their Coulomb-coupled motion, it is more natural to entangle remotely-located ions through a photonic coupling, eliminating the need to control the ion motion. When two atomic ions each become entangled with an emitted single photon, subsequent interference and detection of these photons can leave the trapped ion qubits in an entangled state. Towards this end we have demonstrated single photon emission from a trapped ytterbium ion by exciting the ion with ultrafast laser pulses. Furthermore we have observed the quantum interference between pairs of single photons emitted from two remote trapped ytterbium ions. The same two ions are used to generate thousands of two-photon interference events, which, together with the long coherence times available in trapped ion systems, points the way toward scaling to large entangled networks of remote qubits.