title: Randomized benchmarking of quantum gates implemented by electron spin resonance.
abstract: Spin systems controlled and probed by magnetic resonance have been valuable for testing the ideas of quantum control and quantum error correction. This paper introduces an X-band pulsed electron spin resonance spectrometer designed for high-fidelity coherent control of electron spins, including a loop-gap resonator for sub-millimeter sized samples with a control bandwidth ∼40MHz. Universal control is achieved by a single-sideband upconversion technique with an I-Q modulator and a 1.2GS/s arbitrary waveform generator. A single qubit randomized benchmarking protocol quantifies the average errors of Clifford gates implemented by simple Gaussian pulses, using a sample of gamma-irradiated quartz. Improvements in unitary gate fidelity are achieved through phase transient correction and hardware optimization. A preparation pulse sequence that selects spin packets in a narrowed distribution of static fields confirms that inhomogeneous dephasing (1/T2(∗)) is the dominant source of gate error. The best average fidelity over the Clifford gates obtained here is 99.2%, which serves as a benchmark to compare with other technologies.
authors.affiliation: Institute for Quantum Computing, Waterloo, Ontario N2L 3G1, Canada; Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Park
authors.affiliation: Institute for Quantum Computing, Waterloo, Ontario N2L 3G1, Canada; Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Guanru
authors.initials: G
authors.lastname: Feng
authors.affiliation: Institute for Quantum Computing, Waterloo, Ontario N2L 3G1, Canada; Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Robabeh
authors.initials: R
authors.lastname: Rahimi
authors.affiliation: Institute for Quantum Computing, Waterloo, Ontario N2L 3G1, Canada; Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada; Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. Electronic address: baugh@uwaterloo.ca.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Baugh
authors.affiliation: Institute for Quantum Computing, Waterloo, Ontario N2L 3G1, Canada; Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada; Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2J 2W9, Canada; Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada.
authors.forename: Raymond
authors.initials: R
authors.lastname: Laflamme
keywords: Electron spin resonance; Quantum information processing; Randomized benchmarking