High-fidelity quantum logic gates using trapped-ion hyperfine qubits

Abstract

We demonstrate laser-driven two-qubit and single-qubit logic gates with fidelities 99.9(1)% and 99.9934(3)% respectively, significantly above the approximately 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$\mu$s and 520$\mu$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.