title: High-Fidelity Trapped-Ion Quantum Logic Using Near-Field Microwaves.
abstract: We demonstrate a two-qubit logic gate driven by near-field microwaves in a room-temperature microfabricated surface ion trap. We introduce a dynamically decoupled gate method, which stabilizes the qubits against fluctuating energy shifts and avoids the need to null the microwave field. We use the gate to produce a Bell state with fidelity 99.7(1)%, after accounting for state preparation and measurement errors. The gate is applied directly to ^{43}Ca^{+} hyperfine "atomic clock" qubits (coherence time T_{2}^{*}≈50  s) using the oscillating magnetic field gradient produced by an integrated microwave electrode.
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: T P
authors.initials: TP
authors.lastname: Harty
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: M A
authors.initials: MA
authors.lastname: Sepiol
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: D T C
authors.initials: DT
authors.lastname: Allcock
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: C J
authors.initials: CJ
authors.lastname: Ballance
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: J E
authors.initials: JE
authors.lastname: Tarlton
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: D M
authors.initials: DM
authors.lastname: Lucas