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DOE OSTI · 1853555

Efficient Estimation of Pauli Observables by Derandomization

Huang, Hsin-Yuan·Kueng, Richard·Preskill, John
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Abstract

In this work, we consider the problem of jointly estimating expectation values of many Pauli observables, a crucial subroutine in variational quantum algorithms. Starting with randomized measurements, we propose an efficient derandomization procedure that iteratively replaces random single-qubit measurements by fixed Pauli measurements; the resulting deterministic measurement procedure is guaranteed to perform at least as well as the randomized one. In particular, for estimating any L low-weight Pauli observables, a deterministic measurement on only of order log(L) copies of a quantum state suffices. In some cases, for example, when some of the Pauli observables have high weight, the derandomized procedure is substantially better than the randomized one. Specifically, numerical experiments highlight the advantages of our derandomized protocol over various previous methods for estimating the ground-state energies of small molecules.

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71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICSPhysicsQuantum computationQuantum protocolsQuantum tomography

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Huang, Hsin-Yuan, Kueng, Richard, Preskill, John. 2021-07-16. Efficient Estimation of Pauli Observables by Derandomization. https://doi.org/10.1103/physrevlett.127.030503

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