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Quantum-Selected Configuration Interaction: classical diagonalization of Hamiltonians in subspaces selected by quantum computers

32 Pith papers cite this work, alongside 15 external citations. Polarity classification is still indexing.

32 Pith papers citing it
15 external citations · Pith
abstract

We propose quantum-selected configuration interaction (QSCI), a class of hybrid quantum-classical algorithms for calculating the ground- and excited-state energies of many-electron Hamiltonians on noisy quantum devices. Suppose that an approximate ground state can be prepared on a quantum computer either by variational quantum eigensolver or by some other method. Then, by sampling the state in the computational basis, which is hard for classical computation in general, one can identify the electron configurations that are important for reproducing the ground state. The Hamiltonian in the subspace spanned by those important configurations is diagonalized on classical computers to output the ground-state energy and the corresponding eigenvector. The excited-state energies can be obtained similarly. The result is robust against statistical and physical errors because the noisy quantum devices are used only to define the subspace, and the resulting ground-state energy strictly satisfies the variational principle even in the presence of such errors. The expectation values of various other operators can also be estimated for obtained eigenstates with no additional quantum cost, since the explicit eigenvectors in the subspaces are known. We verified our proposal by numerical simulations, and demonstrated it on a quantum device for an 8-qubit molecular Hamiltonian. The proposed algorithms are potentially feasible to tackle some challenging molecules by exploiting quantum devices with several tens of qubits, assisted by high-performance classical computing resources for diagonalization.

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representative citing papers

Polynomial-time exact diagonalization via sparse guided eigenwalks

quant-ph · 2026-06-22 · unverdicted · novelty 8.0

Introduces the eigenwalk problem and proves a linear-diameter support-localization theorem for sparse eigenvectors, yielding poly(n)-time classical exact diagonalization for O(1)-sparse extremal eigenvectors of poly(n)-sparse 2^n-dimensional Hamiltonians.

Generative Quantum-inspired Kolmogorov-Arnold Eigensolver

quant-ph · 2026-05-06 · unverdicted · novelty 7.0

GQKAE uses quantum-inspired Kolmogorov-Arnold networks to reduce parameters by 66% in generative quantum eigensolvers while achieving chemical accuracy on H4, N2, LiH, and other molecules.

Absorbing Many-Body Correlations into Core-Optimized Orbitals

quant-ph · 2026-05-21 · unverdicted · novelty 6.0

COO co-optimizes orbitals with TrimCI to absorb many-body correlations into the basis, cutting determinant count by orders of magnitude for iron-sulfur clusters versus localized bases or DMRG.

Forecasts of CMB $E$-mode anomalies for AliCPT-1

astro-ph.CO · 2026-04-22 · conditional · novelty 6.0

A divide-and-conquer framework using QAOA and neural network surrogates accelerates constrained MCMC by factors of 7.6 to 20.3 over classical methods.

Tensor-based phase difference estimation on time series analysis

quant-ph · 2026-01-22 · unverdicted · novelty 6.0

Tensor-network compression of nearest-neighbor circuits plus four-type measurements yields 0.4-4.7% error on 8-qubit Hubbard energy gaps and enables QPE-type runs on IBM devices up to 52 qubits with over 4000 two-qubit gates.

ffsim: Faster simulation of fermionic quantum circuits

quant-ph · 2026-05-04 · unverdicted · novelty 5.0

ffsim is a new open-source library that accelerates fermionic quantum circuit simulation by using particle number and spin symmetries to cut memory and runtime, outperforming FQE on benchmarks up to 64 qubits.

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Showing 32 of 32 citing papers.