From noisy observables to accurate ground state energies: a quantum classical signal subspace approach with denoising

Hardeep Bassi; Yizhi Shen; Harish S. Bhat; Roel Van Beeumen

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arXiv · 2505.10735

From noisy observables to accurate ground state energies: a quantum classical signal subspace approach with denoising

Hardeep Bassi·Yizhi Shen·Harish S. Bhat·Roel Van Beeumen

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Abstract

We propose a hybrid quantum-classical algorithm for ground state energy (GSE) estimation that remains robust to highly noisy data and exhibits low sensitivity to hyperparameter tuning. Our approach -- Fourier Denoising Observable Dynamic Mode Decomposition (FDODMD) -- combines Fourier-based denoising thresholding to suppress spurious noise modes with observable dynamic mode decomposition (ODMD), a quantum-classical signal subspace method. By applying ODMD to an ensemble of denoised time-domain trajectories, FDODMD reliably estimates the system's eigenfrequencies. We also provide an error analysis of FDODMD. Numerical experiments on molecular systems demonstrate that FDODMD achieves convergence in high-noise regimes inaccessible to baseline methods under a limited quantum computational budget, while accelerating spectral estimation in intermediate-noise regimes. Importantly, this performance gain is entirely classical, requiring no additional quantum overhead and significantly reducing overall quantum resource demands.

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Hardeep Bassi, Yizhi Shen, Harish S. Bhat, Roel Van Beeumen. 2025-05-15. From noisy observables to accurate ground state energies: a quantum classical signal subspace approach with denoising. https://arxiv.org/abs/2505.10735

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