Combining dynamical-decoupling pulses with optimal control theory for improved quantum gates Matthew D. Grace ∗ Department of Scalable & Secure Systems Research (08961), Sandia National Laboratories, Livermore, CA 94550 Jason Dominy † Program in Applied & Computational Mathematics, Princeton University, Princeton, New Jersey 08544 Wayne M. Witzel ‡ Department of Advanced Device Technologies (01425), Sandia National Laboratories, Albuquerque, NM 87185 Malcolm S. Carroll § Department of Photonic Microsystem Technologies (01725), Sandia National Laboratories, Albuquerque, NM 87185 (Dated: May 13, 2011) Constructing high-fidelity control pulses that are robust to control and sys- tem/environment fluctuations is a crucial objective for quantum information process- ing. Using the two-state Landau-Zener model for simulations of a double quantum dot qubit, we generate optimal controls for π- and π/2-pulses, and investigate their inherent robustness. We find enhanced robustness through a novel combination of recent results from dynamical-decoupling and optimal control of unitary operations. Previous work has shown that general errors up to (but not including) third order can be removed from π- and π/2-pulses without concatenation. By systematically integrating methods from dynamical-decoupling and optimal control, and incorpo- rating system parameter estimates, we demonstrate, via a numerical example, that gate fidelity may further be improved. * Electronic address: mgrace@sandia.gov arXiv:1105.2358v1 [quant-ph] 12 May 2011