Classical reservoir approach for efficient molecular ground state preparation

2025/12/24 by Zekun He, Dominika Zgid, He, Zekun +5
Computer Science · Materials Science · Physics and Astronomy · #FOS: Physical sciences #Machine Learning in Materials Science #Quantum Computing Algorithms and Architecture #Quantum Physics (quant-ph) #Spectroscopy and Quantum Chemical Studies

paper · doi:10.48550/arxiv.2512.21069

openalex publication_date 2025/12/24 · openalex created_date 2025/12/26 · openalex updated_date 2026/07/28

Abstract

Ground state preparation is a central application of quantum algorithms for electronic structure. We introduce the classical reservoir approach, a low cost variational ansatz tailored to near-term hardware, requiring only nearest-neighbor interactions on a machine with square-lattice connectivity. Unlike traditional methods built from the classically efficient Hartree Fock theory, our ansatz operates in localized molecular orbitals to study previously unexplored regions of the variational parameter space. Numerical benchmarks demonstrate chemical accuracy across diverse systems and bond lengths; notably, significantly reduced circuit depths are attainable when relaxed error thresholds (e.g., tens of E_h) are permissible. We benchmark the method on hydrogen chains, N₂, O₂, CO, BeH₂, and H₂O, the latter corresponding to an effective 24 qubit calculation.

Citations

• Efficient Fermi-Hubbard model ground-state preparation by coupling to a classical reservoir in the instantaneous-response limit
• Non-Variational ADAPT algorithm for quantum simulations
• Rapid initial state preparation for the quantum simulation of strongly correlated molecules
• Quantum error correction below the surface code threshold
• Subspace methods for electronic structure simulations on quantum computers
• Low-Depth Unitary Coupled Cluster Theory for Quantum Computation
• A Quantum-Inspired Algorithm for the Factorized Form of Unitary Coupled Cluster Theory
• Recent developments in the PySCF program package

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