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Bibliographic Details
Main Author: Davis, Devin Phillip
Format: Recurso digital
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Published: Zenodo 2026
Online Access:https://doi.org/10.5281/zenodo.19864030
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Table of Contents:
  • <p>We introduce a hardware-native robustness metric for parameterized quantum circuits (PQCs) based on the Wasserstein-2 (<span class="math-inline">$W_2$</span>) distance between output probability distributions across replicates, requiring no classical simulation or ideal-state reference. We apply this framework to a golden-spiral entanglement circuit on a 27-qubit subset of <code>ibm_fez</code> (156-qubit IBM Heron r2 processor), sweeping the initial rotation angle. The central hypothesis — that the square of the golden ratio provides superior distributional robustness — is falsified: the lower-angle configuration achieves 28% higher robustness. A strong inverse correlation between output entropy and distributional robustness is observed, suggesting that conservative parameterization — which preserves low-entropy structured attractors — provides greater shot-to-shot reproducibility on NISQ hardware than maximally expressive parameterizations. We characterize the mechanism: the low-angle circuit preserves a 112×-enhanced probability mode at the all-ones computational basis state, while the high-entropy circuits produce near-uniform distributions with large inter-replicate variation. These results have implications for noise-aware circuit design, VQE/QAOA initialization, and NISQ benchmarking methodology.</p>