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Main Authors: Kesiku, Cyrille Yetuyetu, Garcia-Zapirain, Begonya
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2603.16321
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author Kesiku, Cyrille Yetuyetu
Garcia-Zapirain, Begonya
author_facet Kesiku, Cyrille Yetuyetu
Garcia-Zapirain, Begonya
contents Attributing performance gains in quantum machine learning to genuine quantum resources rather than to classical architectural scaling remains an open methodological challenge. We address this by introducing a counterfactual causal mediation framework that decomposes inter-architectural performance differences into direct effects, attributable to circuit parameterization and expressivity, and indirect effects mediated by quantum information-theoretic observables: entanglement entropy, purity, linear entropy, and quantum mutual information. Applying this framework to five circuit topologies and three benchmark datasets (across 43 validated configurations) reveals that direct architectural contributions systematically exceed quantum-mediated effects, with a mean ratio of 13.1:1 and a mean indirect contribution of 0.82%. These results suggest that current variational quantum circuits operate substantially below their quantum potential, and that principled resource-aware circuit design represents a tractable path toward measurable quantum-mediated performance gains.
format Preprint
id arxiv_https___arxiv_org_abs_2603_16321
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle How Quantum Circuits Actually Learn: A Causal Identification of Genuine Quantum Contributions
Kesiku, Cyrille Yetuyetu
Garcia-Zapirain, Begonya
Quantum Physics
Quantum Algebra
Attributing performance gains in quantum machine learning to genuine quantum resources rather than to classical architectural scaling remains an open methodological challenge. We address this by introducing a counterfactual causal mediation framework that decomposes inter-architectural performance differences into direct effects, attributable to circuit parameterization and expressivity, and indirect effects mediated by quantum information-theoretic observables: entanglement entropy, purity, linear entropy, and quantum mutual information. Applying this framework to five circuit topologies and three benchmark datasets (across 43 validated configurations) reveals that direct architectural contributions systematically exceed quantum-mediated effects, with a mean ratio of 13.1:1 and a mean indirect contribution of 0.82%. These results suggest that current variational quantum circuits operate substantially below their quantum potential, and that principled resource-aware circuit design represents a tractable path toward measurable quantum-mediated performance gains.
title How Quantum Circuits Actually Learn: A Causal Identification of Genuine Quantum Contributions
topic Quantum Physics
Quantum Algebra
url https://arxiv.org/abs/2603.16321