Convergence of sample-based quantum diagonalization on a variable-length cuprate chain

Fuente: arXiv
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Main Authors: Wray, L. Andrew, Lin, Cheng-Ju, Su, Vincent, Gharibyan, Hrant
Format: Preprint
Published: 2025
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author Wray, L. Andrew
Lin, Cheng-Ju
Su, Vincent
Gharibyan, Hrant
author_facet Wray, L. Andrew
Lin, Cheng-Ju
Su, Vincent
Gharibyan, Hrant
contents Sample-based quantum diagonalization (SQD) is an algorithm for hybrid quantum-classical molecular simulation that has been of broad interest for application with noisy intermediate scale quantum (NISQ) devices. However, SQD does not always converge on a practical timescale. Here, we explore scaling of the algorithm for a variable-length molecule made up of 2 to 6 copper oxide plaquettes with a minimal molecular orbital basis. The results demonstrate that enabling all-to-all connectivity, instituting a higher expansion order for the SQD algorithm, and adopting a non-Hartree-Fock molecular orbital basis can all play significant roles in overcoming sampling bottlenecks, though with tradeoffs that need to be weighed against the capabilities of quantum and classical hardware. Additionally, we find that noise on a real quantum computer, the Quantinuum H2 trapped ion device, can improve energy convergence beyond expectations based on noise-free statevector simulations.
format Preprint
id arxiv_https___arxiv_org_abs_2512_04962
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Convergence of sample-based quantum diagonalization on a variable-length cuprate chain
Wray, L. Andrew
Lin, Cheng-Ju
Su, Vincent
Gharibyan, Hrant
Quantum Physics
Other Condensed Matter
Chemical Physics
Computational Physics
Sample-based quantum diagonalization (SQD) is an algorithm for hybrid quantum-classical molecular simulation that has been of broad interest for application with noisy intermediate scale quantum (NISQ) devices. However, SQD does not always converge on a practical timescale. Here, we explore scaling of the algorithm for a variable-length molecule made up of 2 to 6 copper oxide plaquettes with a minimal molecular orbital basis. The results demonstrate that enabling all-to-all connectivity, instituting a higher expansion order for the SQD algorithm, and adopting a non-Hartree-Fock molecular orbital basis can all play significant roles in overcoming sampling bottlenecks, though with tradeoffs that need to be weighed against the capabilities of quantum and classical hardware. Additionally, we find that noise on a real quantum computer, the Quantinuum H2 trapped ion device, can improve energy convergence beyond expectations based on noise-free statevector simulations.
title Convergence of sample-based quantum diagonalization on a variable-length cuprate chain
topic Quantum Physics
Other Condensed Matter
Chemical Physics
Computational Physics
url https://arxiv.org/abs/2512.04962