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Q: Fachverband Quantenoptik und Photonik

Q 55: Poster II

Q 55.54: Poster

Donnerstag, 11. März 2010, 16:00–19:00, Lichthof

Lossless atomic state detection using the Purcell effect — •Carolin Hahn, Jörg Bochmann, Martin Mücke, Christoph Guhl, Stephan Ritter, David Moehring, and Gerhard Rempe — MPI für Quantenoptik, 85748 Garching

One of the diVincenzo criteria for quantum computation is the efficient read-out of the state of the quantum bit (qubit). In single trapped neutral atoms, qubits are typically encoded in or mapped onto atomic hyperfine states. Detection of these hyperfine states often suffers from loss of the atom. Further, the speed and efficiency in schemes relying on spontaneous emission in free space is limited by the photon collection efficiency. Making use of the Purcell effect in an optical cavity, a controlled coupling between qubit and environment can be established, suitable for in an improved state detection scheme based on cavity-enhanced fluorescence. With this method we achieve a hyperfine state detection fidelity of 99.4% in 85 µs in our experiment with a single trapped ⁸⁷Rb atom. A result is obtained in every read-out attempt and, most importantly, the qubit can be interrogated many hundred times before the atom is lost from the trap. This presents an essential advancement for the speed and scalability of quantum information protocols based on neutral atoms. Our scheme is applicable to all systems with optically accessible qubits.