Temporal-order-controlled Parrondo reversal in a periodically switched quantum walk acting on NEQR image states

Abstract:We study a coherent reversible map of novel enhanced quantum representation (NEQR) image states, combining public permutations with a classically controlled Parrondo discrete-time quantum walk on the color register. Inversion retains every register coherently. An exact-expectation sweep with an effect-size threshold identifies five cases in which two losing fixed-coin walks form a winning switched walk. At the selected point, exhaustive enumeration supplies a matched temporal-order control: with identical angles, length, initialization, and coin counts, \(00111\) yields \(\Delta_C=+7.21\), whereas \(01101\) yields \(\Delta_C=-8.96\). Translation covariance makes each conditional output-color distribution a shifted copy of one exact walk kernel. Exact diagnostics expose finite-shot artifacts and repeated-copy relative-shift leakage. They demonstrate an order effect, but neither a reversal-caused scrambling advantage nor cryptographic security. We additionally quantify finite-shot convergence, wrong-control sensitivity, and a depolarizing-noise basis-recovery bound. Resource estimates show that arbitrary NEQR preparation dominates the \(O(q^2+qr)\) walk layer, delimiting the scope of the construction.

arXiv:2508.16382 [quant-ph]

(or arXiv:2508.16382v4 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2508.16382 Focus to learn more arXiv-issued DOI via DataCite

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