Fidelity-Based Robustness Margins for Finite-Time Quantum Control

Abstract:We develop a structure-specific fidelity-threshold robustness margin for finite-dimensional closed quantum systems under piecewise-constant coherent control. A scalar physical parameter may perturb the drift, a control Hamiltonian, or another declared Hamiltonian component across the control horizon. A differential sensitivity bound for trace-amplitude gate fidelity yields a threshold-dependent Lipschitz constant on the connected safe parameter component and hence a certified finite perturbation radius. Recentering this certificate produces an iterative one-dimensional method that takes certified safe steps toward the first fidelity-threshold boundary in either parameter direction. A three-qubit gate-control example shows that these finite margins vary by up to a factor of three across controllers of comparable nominal fidelity and contain structure-dependent information not captured by nominal differential sensitivity alone.

Quantum Physics (quant-ph); Systems and Control (eess.SY)

arXiv:2608.03698 [quant-ph]

(or arXiv:2608.03698v1 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2608.03698 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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