Density matrix based perturbative corrections for improved quantum simulation accuracy

We present error mitigation (EM) techniques for noisy intermediate-scale quantum computers (QC) based on density matrix purification and perturbative corrections to the target energy. We incorporate this scheme into the variational quantum eigensolver (VQE) and demonstrate chemically-accurate ground...

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Bibliographic Details
Published in:arXiv.org 2019-12
Main Authors: Morris, T D, Parks, Z P, McCaskey, A J, Jakowski, J, Pooser, R C
Format: Article
Language:English
Subjects:
Accuracy
Alkali metals
Computer simulation
Density
Error correction
Metal hydrides
Optimization
Organic chemistry
Post-processing
Purification
Quantum computers
Quantum computing
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Summary:We present error mitigation (EM) techniques for noisy intermediate-scale quantum computers (QC) based on density matrix purification and perturbative corrections to the target energy. We incorporate this scheme into the variational quantum eigensolver (VQE) and demonstrate chemically-accurate ground state energy calculations of various alkali metal hydrides using IBM quantum computers. Both the density matrix purification improvements and the perturbative corrections require only meager classical computational resources, and are conducted exclusively as post-processing of the measured density matrix. The improved density matrix leads to better simulation accuracy at each step of the variational optimization, resulting in a better input into the next optimization step without additional measurements. Adding perturbative corrections to the resulting energies further increases the accuracy, and decreases variation between consecutive measurements. These EM schemes allow for previously unavailable levels of accuracy over remote QC resources.
ISSN:2331-8422