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arXiv · 0808.3973

Randomized benchmarking of single and multi-qubit control in liquid-state NMR quantum information processing

C. A. Ryan·M. Laforest·R. Laflamme
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Abstract

Being able to quantify the level of coherent control in a proposed device implementing a quantum information processor (QIP) is an important task for both comparing different devices and assessing a device's prospects with regards to achieving fault-tolerant quantum control. We implement in a liquid-state nuclear magnetic resonance QIP the randomized benchmarking protocol presented by Knill et al (PRA 77: 012307 (2008)). We report an error per randomized $\fracπ{2}$ pulse of $1.3 \pm 0.1 \times 10^{-4}$ with a single qubit QIP and show an experimentally relevant error model where the randomized benchmarking gives a signature fidelity decay which is not possible to interpret as a single error per gate. We explore and experimentally investigate multi-qubit extensions of this protocol and report an average error rate for one and two qubit gates of $4.7 \pm 0.3 \times 10^{-3}$ for a three qubit QIP. We estimate that these error rates are still not decoherence limited and thus can be improved with modifications to the control hardware and software.

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C. A. Ryan, M. Laforest, R. Laflamme. 2008-08-28. Randomized benchmarking of single and multi-qubit control in liquid-state NMR quantum information processing. https://doi.org/10.1088/1367-2630%2F11%2F1%2F013034

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