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arXiv · 2603.24728

Auto-regressive Neural Quantum State Sampling for Selected Configuration Interaction

Shane Thompson·Daniel Gunlycke
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Abstract

Accurate ground-state energy calculations remain a central challenge in quantum chemistry due to the exponential scaling of the many-body Hilbert space. Variational Monte Carlo and variational quantum eigensolvers offer promising ansatz optimization approaches but face limitations in convergence as well as hardware constraints. We introduce a particular Selected Configuration Interaction (SCI) algorithm that uses auto-regressive neural networks (ARNNs) to guide subspace expansion for ground-state search. Leveraging the unique properties of ARNNs, our algorithm efficiently constructs compact variational subspaces from learned ground-state statistics, which in turn accelerates convergence to the ground-state energy. Benchmarks on molecular systems demonstrate that ARNN-guided subspace expansion combines the strengths of neural-network representations and classical subspace methods, providing a scalable framework for classical and hybrid quantum-classical algorithms.

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Shane Thompson, Daniel Gunlycke. 2026-03-25. Auto-regressive Neural Quantum State Sampling for Selected Configuration Interaction. https://arxiv.org/abs/2603.24728

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