title: High-Fidelity Preparation, Gates, Memory, and Readout of a Trapped-Ion Quantum Bit.
abstract: We implement all single-qubit operations with fidelities significantly above the minimum threshold required for fault-tolerant quantum computing, using a trapped-ion qubit stored in hyperfine "atomic clock" states of ^{43}Ca^{+}. We measure a combined qubit state preparation and single-shot readout fidelity of 99.93%, a memory coherence time of T_{2}^{*}=50  sec, and an average single-qubit gate fidelity of 99.9999%. These results are achieved in a room-temperature microfabricated surface trap, without the use of magnetic field shielding or dynamic decoupling techniques to overcome technical noise.
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: T P
authors.initials: TP
authors.lastname: Harty
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: D T C
authors.initials: DT
authors.lastname: Allcock
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: C J
authors.initials: CJ
authors.lastname: Ballance
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom and Laboratoire Matériaux et Phénomènes Quantiques, University of Paris Diderot, UMR 7162 CNRS, F-75205 Paris, France.
authors.forename: L
authors.initials: L
authors.lastname: Guidoni
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: H A
authors.initials: HA
authors.lastname: Janacek
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: N M
authors.initials: NM
authors.lastname: Linke
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: D N
authors.initials: DN
authors.lastname: Stacey
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: D M
authors.initials: DM
authors.lastname: Lucas