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Published July 5, 2011 | Published
Journal Article Open

Combining dynamical decoupling with fault-tolerant quantum computation


We study how dynamical decoupling (DD) pulse sequences can improve the reliability of quantum computers. We prove upper bounds on the accuracy of DD-protected quantum gates and derive sufficient conditions for DD-protected gates to outperform unprotected gates. Under suitable conditions, fault-tolerant quantum circuits constructed from DD-protected gates can tolerate stronger noise and have a lower overhead cost than fault-tolerant circuits constructed from unprotected gates. Our accuracy estimates depend on the dynamics of the bath that couples to the quantum computer and can be expressed either in terms of the operator norm of the bath's Hamiltonian or in terms of the power spectrum of bath correlations; we explain in particular how the performance of recursively generated concatenated pulse sequences can be analyzed from either viewpoint. Our results apply to Hamiltonian noise models with limited spatial correlations.

Additional Information

© 2011 American Physical Society. Received 1 April 2011; published 5 July 2011. Research of H.K.N. and J.P. is supported by NSF under Grant No. PHY-0803371. J.P.'s research is also supported by the DOE under Grant No. DE-FG03-92-ER40701, and by NSA/ARO under Grant No. W911NF-09-1-0442. D.A.L. thanks the Institute for Quantum Information at Caltech, where this work was done, and acknowledges funding from the US Department of Defense, Grants No. NSF PHY-803304, No. NSF PHY-802678, and No. NSF CCF-726439. We thank Kurt Litsch for doing a numerical analysis of the recursion relations in Sec. VIIIA and for suggesting ways to improve some of our arguments.

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Published - Ng2011p14796Phys_Rev_A.pdf


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