Adaptive optimal control of entangled qubits

David L. Goodwin, Pranav Singh, Mohammadali Foroozandeh

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2 Citations (SciVal)
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Developing fast, robust, and accurate methods for optimal control of quantum systems comprising interacting particles is one of the most active areas of current science. Although a valuable repository of algorithms is available for numerical applications in quantum control, the high computational cost is somewhat overlooked. Here, we present a fast and accurate optimal control algorithm for systems of interacting qubits, QOALA (quantum optimal control by adaptive low-cost algorithm), which is predicted to offer O(M 2) speedup for an M-qubit system, compared to the state-of-the-art exact methods, without compromising overall accuracy of the optimal solution. The method is general and compatible with diverse Hamiltonian structures. The proposed approach uses inexpensive low-accuracy approximations of propagators far from the optimum, adaptively switching to higher accuracy, higher-cost propagators when approaching the optimum. In addition, the utilization of analytical Lie algebraic derivatives that do not require computationally expensive matrix exponential brings even better performance.

Original languageEnglish
Article numbereabq4244
JournalScience Advances
Issue number49
Publication statusPublished - 7 Dec 2022

Bibliographical note

Funding Information:
Funding: M.F. is grateful to the Royal Society for a University Research Fellowship and a University Research Fellow Enhancement Award (URF\R1\180233 and RGF\EA\181018) that have funded this project.

Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and are also publicly hosted on GitHub ( and Zenodo ( in the form of a MATLAB toolbox QOALA, which includes functions to produce the results presented in this paper and an additional set of examples.

ASJC Scopus subject areas

  • General


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