



01589nas a2200193   4500008004100000245008100041210006900122260001500191300001100206490000700217520100800224100002301232700002501255700001901280700001901299700002001318700002101338856003601359       2015                        eng d00aDemonstration of Robust Quantum Gate Tomography via Randomized  Benchmarking0 aDemonstration of Robust Quantum Gate Tomography via Randomized B  c2015/11/05  a1130190 v173 a  Typical quantum gate tomography protocols struggle with a self-consistency
problem: the gate operation cannot be reconstructed without knowledge of the
initial state and final measurement, but such knowledge cannot be obtained
without well-characterized gates. A recently proposed technique, known as
randomized benchmarking tomography (RBT), sidesteps this self-consistency
problem by designing experiments to be insensitive to preparation and
measurement imperfections. We implement this proposal in a superconducting
qubit system, using a number of experimental improvements including
implementing each of the elements of the Clifford group in single `atomic'
pulses and custom control hardware to enable large overhead protocols. We show
a robust reconstruction of several single-qubit quantum gates, including a
unitary outside the Clifford group. We demonstrate that RBT yields physical
gate reconstructions that are consistent with fidelities obtained by randomized
benchmarking.
1 aJohnson, Blake, R.1 ada Silva, Marcus, P.1 aRyan, Colm, A.1 aKimmel, Shelby1 aChow, Jerry, M.1 aOhki, Thomas, A.  uhttp://arxiv.org/abs/1505.0668601337nas a2200169   4500008004100000245007700041210006900118260001400187490000600201520082000207100001901027700002501046700001901071700002301090700001701113856003701130       2014                        eng d00aRobust Extraction of Tomographic Information via Randomized Benchmarking0 aRobust Extraction of Tomographic Information via Randomized Benc  c2014/3/250 v43 a  We describe how randomized benchmarking can be used to reconstruct the unital
part of any trace-preserving quantum map, which in turn is sufficient for the
full characterization of any unitary evolution, or more generally, any unital
trace-preserving evolution. This approach inherits randomized benchmarking's
robustness to preparation and measurement imperfections, therefore avoiding
systematic errors caused by these imperfections. We also extend these
techniques to efficiently estimate the average fidelity of a quantum map to
unitary maps outside of the Clifford group. The unitaries we consider include
operations commonly used to achieve universal quantum computation in a
fault-tolerant setting. In addition, we rigorously bound the time and sampling
complexities of randomized benchmarking procedures.
1 aKimmel, Shelby1 ada Silva, Marcus, P.1 aRyan, Colm, A.1 aJohnson, Blake, R.1 aOhki, Thomas  uhttp://arxiv.org/abs/1306.2348v1