High-Fidelity Trapped-Ion Quantum Logic Using Near-Field Microwaves

T. P. Harty, M. A. Sepiol, D. T. C. Allcock, C. J. Ballance, J. E. Tarlton, and D. M. Lucas

Physical Review Letters

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 43Ca+ hyperfine “atomic clock” qubits (coherence time T∗2≈50  s) using the oscillating magnetic field gradient produced by an integrated microwave electrode.

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