title: Demonstration of qubit operations below a rigorous fault tolerance threshold with gate set tomography.
abstract: Quantum information processors promise fast algorithms for problems inaccessible to classical computers. But since qubits are noisy and error-prone, they will depend on fault-tolerant quantum error correction (FTQEC) to compute reliably. Quantum error correction can protect against general noise if-and only if-the error in each physical qubit operation is smaller than a certain threshold. The threshold for general errors is quantified by their diamond norm. Until now, qubits have been assessed primarily by randomized benchmarking, which reports a different error rate that is not sensitive to all errors, and cannot be compared directly to diamond norm thresholds. Here we use gate set tomography to completely characterize operations on a trapped-Yb+-ion qubit and demonstrate with greater than 95% confidence that they satisfy a rigorous threshold for FTQEC (diamond norm ≤6.7 × 10-4).
authors.affiliation: Center for Computing Research, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
authors.forename: Robin
authors.initials: R
authors.lastname: Blume-Kohout
authors.affiliation: Center for Computing Research, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
authors.forename: John King
authors.initials: JK
authors.lastname: Gamble
authors.affiliation: Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
authors.forename: Erik
authors.initials: E
authors.lastname: Nielsen
authors.affiliation: Center for Computing Research, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Rudinger
authors.affiliation: Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Mizrahi
authors.affiliation: Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Fortier
authors.affiliation: Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Maunz