Low-cost error mitigation by symmetry verification

X. Bonet-Monroig, R. Sagastizabal, M. Singh, T. E. O'Brien

Research output: Contribution to journalArticleScientificpeer-review

120 Citations (Scopus)
111 Downloads (Pure)


We investigate the performance of error mitigation via measurement of conserved symmetries on near-term devices. We present two protocols to measure conserved symmetries during the bulk of an experiment, and develop a third, zero-cost, post-processing protocol which is equivalent to a variant of the quantum subspace expansion. We develop methods for inserting global and local symmetries into quantum algorithms, and for adjusting natural symmetries of the problem to boost the mitigation of errors produced by different noise channels. We demonstrate these techniques on two- and four-qubit simulations of the hydrogen molecule (using a classical density-matrix simulator), finding up to an order of magnitude reduction of the error in obtaining the ground-state dissociation curve.

Original languageEnglish
Article number062339
Number of pages10
JournalPhysical Review A
Issue number6
Publication statusPublished - 2018


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