Qubit-excitation-based adaptive variational quantum eigensolver
Publication Date
2021-10-14Journal Title
Communications Physics
Publisher
Nature Publishing Group UK
Volume
4
Issue
1
Language
en
Type
Article
This Version
VoR
Metadata
Show full item recordCitation
Yordanov, Y. S., Armaos, V., Barnes, C. H. W., & Arvidsson-Shukur, D. R. M. (2021). Qubit-excitation-based adaptive variational quantum eigensolver. Communications Physics, 4 (1) https://doi.org/10.1038/s42005-021-00730-0
Abstract
Abstract: Molecular simulations with the variational quantum eigensolver (VQE) are a promising application for emerging noisy intermediate-scale quantum computers. Constructing accurate molecular ansätze that are easy to optimize and implemented by shallow quantum circuits is crucial for the successful implementation of such simulations. Ansätze are, generally, constructed as series of fermionic-excitation evolutions. Instead, we demonstrate the usefulness of constructing ansätze with "qubit-excitation evolutions”, which, contrary to fermionic excitation evolutions, obey "qubit commutation relations”. We show that qubit excitation evolutions, despite the lack of some of the physical features of fermionic excitation evolutions, accurately construct ansätze, while requiring asymptotically fewer gates. Utilizing qubit excitation evolutions, we introduce the qubit-excitation-based adaptive (QEB-ADAPT)-VQE protocol. The QEB-ADAPT-VQE is a modification of the ADAPT-VQE that performs molecular simulations using a problem-tailored ansatz, grown iteratively by appending evolutions of qubit excitation operators. By performing classical numerical simulations for small molecules, we benchmark the QEB-ADAPT-VQE, and compare it against the original fermionic-ADAPT-VQE and the qubit-ADAPT-VQE. In terms of circuit efficiency and convergence speed, we demonstrate that the QEB-ADAPT-VQE outperforms the qubit-ADAPT-VQE, which to our knowledge was the previous most circuit-efficient scalable VQE protocol for molecular simulations.
Keywords
Article, /639/766/483/3926, /639/766/94, article
Sponsorship
Hitachi (Hitachi Group) (RG97399)
RCUK | Engineering and Physical Sciences Research Council (EPSRC) (RG97399)
Identifiers
s42005-021-00730-0, 730
External DOI: https://doi.org/10.1038/s42005-021-00730-0
This record's URL: https://www.repository.cam.ac.uk/handle/1810/329483
Rights
Licence:
http://creativecommons.org/licenses/by/4.0/
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