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Q: Fachverband Quantenoptik und Photonik
Q 2: Quanteninformation: Atome und Ionen I
Q 2.3: Talk
Monday, March 2, 2009, 11:15–11:30, ESA-B
High fidelity entanglement of 43Ca+ hyperfine clock states — •Gerhard Kirchmair1,2, Rene Gerritsma1,2, Florian Zähringer1,2, Jan Benhelm1,2, Christian Roos1,2, and Rainer Blatt1,2 — 1Institut für Experimentalphysik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria — 2Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Otto-Hittmair-Platz 1, A-6020 Innsbruck, Austria
In an experiment using the odd calcium isotope 43Ca+ we combine the merits of a high fidelity entangling operation on an optical transition (optical qubit) with the long coherence times offered by two "clock" states in the hyperfine ground state (hyperfine qubit) by mapping between these two qubits. We achieve state initialization, state detection, global qubit rotations and mapping operations with errors smaller than 1%, whereas the Mølmer-Sørensen entangling gate adds errors of 2.3%. We create Bell states with a fidelity of 96.9(3)% in the optical qubit and a fidelity of 96.7(3)% when mapped to the hyperfine states. In the latter case the entanglement is preserved for 96(3) ms, exceeding the gate duration by three orders of magnitude. The Bell state stored in the hyperfine qubit can be mapped back to the optical qubit and additional gate operations disentangle/entangle the ions again. In addition we present results on entangling three 40Ca+ ions in a GHZ state with a fidelity of 98%.