Cited by 2,982Quantum Computing Algorithms and ArchitectureQuantum many-body systemsAdvanced Chemical Physics Studies

Hardware-efficient variational quantum eigensolver for small molecules and quantum magnets

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Kandala, Abhinav, Mezzacapo, Antonio, Temme, Kristan, Takita, Maika, Brink, Markus, Chow, Jerry M., Gambetta, Jay M.·2017·Nature

Abstract

Quantum computers can be used to address electronic-structure problems and problems in materials science and condensed matter physics that can be formulated as interacting fermionic problems, problems which stretch the limits of existing high-performance computers. Finding exact solutions to such problems numerically has a computational cost that scales exponentially with the size of the system, and Monte Carlo methods are unsuitable owing to the fermionic sign problem. These limitations of classical computational methods have made solving even few-atom electronic-structure problems interesting for implementation using medium-sized quantum computers. Yet experimental implementations have so far been restricted to molecules involving only hydrogen and helium. Here we demonstrate the experimental optimization of Hamiltonian problems with up to six qubits and more than one hundred Pauli terms, determining the ground-state energy for molecules of increasing size, up to BeH 2. We achieve this result by using a variational quantum eigenvalue solver (eigensolver) with efficiently prepared trial states that are tailored specifically to the interactions that are available in our quantum processor, combined with a compact encoding of fermionic Hamiltonians and a robust stochastic optimization routine. We demonstrate the flexibility of our approach by applying it to a problem of quantum magnetism, an antiferromagnetic Heisenberg model in an external magnetic field. In all cases, we find agreement between our experiments and numerical simulations using a model of the device with noise. Our results help to elucidate the requirements for scaling the method to larger systems and for bridging the gap between key problems in high-performance computing and their implementation on quantum hardware.

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Crossref · 10.1038/nature23879

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42 of 42 references verified0 citation errors · 0 not checkable

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  • Pauli strings that commute qubit-wise can be measured at the same time.

    “Pauli strings that commute qubit-wise, i.e. the Pauli operators on each qubit commute, can be measured at the same time (Kandala et al. , 2017; McClean et al. , 2016).”

    From Noisy intermediate-scale quantum algorithms (2022) · cites this paper as Kandala et al., 2017

  • A class of hardware-efficient ansätze has been proposed to accommodate device constraints.

    “Aclass of hardware-efficient ansätze (see Fig. 3(b)) has been proposed to accommodate device constraints (Kandala et al. , 2017).”

    From Noisy intermediate-scale quantum algorithms (2022) · cites this paper as Kandala et al., 2017

  • #BQP has been defined and shown to contain important physical problems, but it is of equal complexity to #P.

    “While the quantum analog of #P , #BQP , has been defined and has been shown to contain important physical problems, it turns out to be of equal complexity to #P 67 .”

    From Quantum Chemistry in the Age of Quantum Computing (2019) · cites this paper as [67]

  • VQE is the most prominent hybrid algorithm for electronic structure, providing a variational heuristic for upper-bounding ground-state energy.

    “The most prominent example of this class of algorithms relevant for electronic structure calculations is the variational quantum eigensolver (VQE), which presents a variational (and thus heuristic) algorithm to upper bounding the ground state energy problem.[126][127][128]”

    From Quantum Computing for Molecular Biology** (2023) · cites this paper as [127]

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Authors
Kandala, A., Mezzacapo, A., Temme, K., Takita, M., Brink, M., Chow, J. M., & Gambetta, J. M.
Affiliations
IBM (United States) (US)
Corresponding author
  • Kandala, Abhinav
  • Mezzacapo, Antonio
Venue
Nature
Published
2017-09
Volume
549
Issue
7671
Pages
242-246
ISSN
  • 0028-0836 (ISSN-L)
  • 1476-4687
OpenAlex
W2755255888
Cited by
2,982
References
43
Citations by year
2026: 334 · 2025: 423 · 2024: 439 · 2023: 419 · 2022: 386 · 2021: 405 · 2020: 284 · 2019: 173 · 2018: 101 · 2017: 15 · 2014: 1
FWCI
93.44
Type
journal article
Language
en
Open access
Locations
  • Nature (publishedVersion)
  • PubMed (publishedVersion)
  • arXiv (Cornell University) (submittedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
  • arXiv (Cornell University)
Topics
  • Physical Sciences › Computer Science › Artificial Intelligence › Quantum Computing Algorithms and Architecture
  • Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Quantum many-body systems
  • Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Advanced Chemical Physics Studies
Keywords
variational quantum eigensolver, quantum simulation, ground state energy, small molecules, lithium hydride, beryllium hydride, Heisenberg model, quantum magnetism, superconducting qubits, stochastic optimization, quantum chemistry, quantum error correction, noise modeling

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