Randomized benchmarking and process tomography for gate errors in a   solid-state qubit
  We present measurements of single-qubit gate errors for a superconducting qubit. Results from quantum process tomography and randomized benchmarking are compared with gate errors obtained from a double pi pulse experiment. Randomized benchmarking reveals a minimum average gate error of 1.1+/-0.3% and a simple exponential dependence of fidelity on the number of gates. It shows that the limits on gate fidelity are primarily imposed by qubit decoherence, in agreement with theory. 
J. M. Chow, J. M. Gambetta, L. Tornberg, Jens Koch, Lev S. Bishop, A.   A. Houck, B. R. Johnson, L. Frunzio, S. M. Girvin, a...