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arXiv · 2603.02715

Correction scheme for molecular total energies from quantum phase estimation under limited qubit resources

Nobuki Inoue·Hisao Nakamura
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Abstract

We propose a practical method for accurately evaluating molecular total energies using a hybrid approach that integrates fault-tolerant quantum computers with classical computing. Our scheme consists of two complementary components: quantum dominant orbital selection (QDOS) and subspace dynamical correlation (SDC). QDOS extracts only the essential active orbitals from the complete active space (CAS) configuration interaction (CI) state on a quantum computer, yielding a compact active space suitable for classical CASCI calculations. SDC then evaluates dynamical-correlation corrections for the CASCI energy using this compact state, which remains tractable on classical machines. To demonstrate that the CAS energy obtained on a quantum computer can be post-corrected by SDC, we examine two frameworks: multireference perturbation theory and tailored coupled-cluster theory. Our scheme enables effective treatment of relatively large molecular systems by combining limited quantum and classical resources.

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Nobuki Inoue, Hisao Nakamura. 2026-03-03. Correction scheme for molecular total energies from quantum phase estimation under limited qubit resources. https://doi.org/10.1002/jcc.70400

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