High-Fidelity Quantum Logic Gates Using Trapped-Ion Hyperfine Qubits

Abstract

We demonstrate laser-driven two-qubit and single-qubit logic gates with respective fidelities 99.9(1)% and 99.9934(3)%, significantly above the $\approx 99\%$ minimum threshold level required for fault-tolerant quantum computation, using qubits stored in hyperfine ground states of calcium-43 ions held in a room-temperature trap. We study the speed-fidelity trade-off for the two-qubit gate, for gate times between $3.8\mu \mathrm{s}$ and $520\mu \mathrm{s}$, and develop a theoretical error model which is consistent with the data and which allows us to identify the principal technical sources of infidelity.