Generative Circuit Design for Quantum-Selected Configuration Interaction

Quantum Physics [Submitted on 10 Apr 2026] Generative Circuit Design for Quantum-Selected Configuration Interaction Ryota Kemmoku, Qi Gao, Shu Kanno, Kimberlee Keithley, Ikko Hamamura, Naoki Yamamoto, Kouhei Nakaji Quantum-selected configuration interaction (QSCI) has emerged as a feasible approach for approximating electronic ground states on noisy quantum devices toward large-system demonstrations. In QSCI, Slater determinants are sampled from a quantum-prepared state, and the Hamiltonian is then diagonalized in the sampled subspace. To create a high-quality subspace under hardware constraints, the design of the state-preparation circuit is crucial. Here, we present a Generative Quantum Eigensolver (GQE)-based framework that optimizes ansatz structures using a Transformer policy trained on the QSCI subspace energy. We validate the framework on N2 in active spaces of up to 32 qubits. We found that the optimized circuits reach chemical precision with substantially lower gate counts than time-evolved circuits. Quantitatively, this corresponds to an average reduction of 98% in the required two-qubit gate count relative to the single-step first-order Trotterized approximation and 83% relative to the qDRIFT approximation. Furthermore, the resulting wavefunctions are competitive with heat-bath configuration interaction (HCI) in terms of compactness. In stretched-bond, strongly correlated regimes, they achieve chemical precision with subspaces that are 50% smaller than those required by HCI. Comments: 17 pages, 9 figures Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2604.09756 [quant-ph]   (or arXiv:2604.09756v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2604.09756 Focus to learn more Submission history From: Ryota Kemmoku [view email] [v1] Fri, 10 Apr 2026 16:00:40 UTC (1,173 KB) Access Paper: HTML (experimental) view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-04 References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)