Rotated-Frame Determinant Discovery for Ground- and Excited-State Quantum Selected Configuration Interaction
Abstract
Quantum Selected Configuration Interaction (QSCI) constructs a variational determinant space from measurements of a prepared electronic state, but finite-shot sampling can repeatedly observe high-probability determinants, limiting efficient discovery of configurations important for an accurate selected-CI description. We introduce rotate--sample--unrotate (RSU) determinant discovery, in which the same state is sampled in complementary orbital frames and the observed rotated determinants generate a finite set of candidates in the canonical basis. The Hamiltonian is then diagonalized in an orthonormal selected-CI space without enumerating the full determinant space. State-targeted orbital frames are constructed from an initial selected-CI wavefunction and its external residual. For excited states, we combine RSU with the generative quantum eigensolver (GQE) to prepare target-specific sampling states. Candidate GQE circuits are evaluated by classical selected-CI diagonalization in finite sampled spaces, so the quantum procedure requires only state preparation and determinant sampling. For N2, exact-state controls isolate the determinant-discovery effect: at the stretched geometry, residual-natural-orbital RSU reaches chemical accuracy with 5,000 shots, compared with 20,000 shots for conventional QSCI. The improvement persists with approximate GQE-prepared states and is also observed for target excited states. These results demonstrate improved finite-shot determinant discovery in QSCI for both ground and excited states.
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BibTeX
@misc{okuno2026rotatedframe,
title = {{Rotated-Frame Determinant Discovery for Ground- and Excited-State Quantum Selected Configuration Interaction}},
author = {Yukihiro Okuno},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.05941},
eprint = {2611.05941},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.05941},
}
RIS
TY - UNPB
TI - Rotated-Frame Determinant Discovery for Ground- and Excited-State Quantum Selected Configuration Interaction
AU - Yukihiro Okuno
PY - 2026
DA - 2026/11/04
PB - arXiv
DO - 10.48550/arxiv.2611.05941
UR - https://arxiv.org/abs/2611.05941
AB - Quantum Selected Configuration Interaction (QSCI) constructs a variational determinant space from measurements of a prepared electronic state, but finite-shot sampling can repeatedly observe high-probability determinants, limiting efficient discovery of configurations important for an accurate selected-CI description. We introduce rotate--sample--unrotate (RSU) determinant discovery, in which the same state is sampled in complementary orbital frames and the observed rotated determinants generate a finite set of candidates in the canonical basis. The Hamiltonian is then diagonalized in an orthonormal selected-CI space without enumerating the full determinant space. State-targeted orbital frames are constructed from an initial selected-CI wavefunction and its external residual. For excited states, we combine RSU with the generative quantum eigensolver (GQE) to prepare target-specific sampling states. Candidate GQE circuits are evaluated by classical selected-CI diagonalization in finite sampled spaces, so the quantum procedure requires only state preparation and determinant sampling. For N_2, exact-state controls isolate the determinant-discovery effect: at the stretched geometry, residual-natural-orbital RSU reaches chemical accuracy with 5,000 shots, compared with 20,000 shots for conventional QSCI. The improvement persists with approximate GQE-prepared states and is also observed for target excited states. These results demonstrate improved finite-shot determinant discovery in QSCI for both ground and excited states.
ER -