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arXiv · 2609.27704

The winner's curse in hardware VQE: drift-differenced remeasurement of finite-shot selection bias

Julen Larrucea
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Abstract

Finite-shot optimization can make noisy variational quantum eigensolver energies look artificially accurate. We studied six molecules on two IBM Heron r3 processors in eight replicated cells. Seven optimizer-selected values fell below the exact active-space eigenvalue by up to mHa. Independent later evaluation of the selected and final parameter points, differenced to remove a common epoch shift, showed that most of the selected advantage disappeared: the primary recovery was (approximate 95% session-level interval). Across the reported aggregation choices, recovery estimates ranged from 0.892 to 0.989. The measured contrast was consistent in scale with finite-shot selection, while calibration drift and other sources of variation remain possible. Accuracy claims based on best-observed hardware VQE values therefore require an independent check.

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Julen Larrucea. 2026-09-23. The winner's curse in hardware VQE: drift-differenced remeasurement of finite-shot selection bias. https://arxiv.org/abs/2609.27704

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