Qualitative differences in the robust controllability of model two-qubit systems
Dey A, Johnsson MT, Burgarth D (2026)
Publication Type: Journal article
Publication year: 2026
Journal
Book Volume: 80
Article Number: 80
Journal Issue: 6
DOI: 10.1140/epjd/s10053-026-01181-4
Abstract
Abstract: Robust control of quantum gates under parameter uncertainty is essential for reliable quantum technologies. While complete knowledge of a Hamiltonian enables accurate control, realistic systems often involve uncertain parameters, making controllability challenging. We investigate two model Hamiltonians with partially unknown continuous parameters and assess their robust controllability using a unified framework that combines both theoretical analysis and numerical simulation. Theoretical analysis is grounded in a Lie-algebraic framework, complemented by a numerical method based on discretizing the continuous uncertain parameter. Furthermore, we introduce a modified fidelity functional with a penalty term to optimize control pulses, thereby enhancing robustness against parameter uncertainty. Within this framework, we analyze two representative systems, revealing qualitative differences in their controllability. Graphic abstract: The figure shows how the minimum control time Tε(N) scales with the ensemble size N for System A and System B. The black dots on the curve depict the minimum control time Tε(N) for a target error ε=10-3 within ω∈[1,2]. Solid lines indicate the scaling behaviour for the CNOT gate and dashed lines correspond to the scaling for the generic unitary U given in Eq. (25) (Figure presented.)
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APA:
Dey, A., Johnsson, M.T., & Burgarth, D. (2026). Qualitative differences in the robust controllability of model two-qubit systems. European Physical Journal D, 80(6). https://doi.org/10.1140/epjd/s10053-026-01181-4
MLA:
Dey, Anirban, Mattias T. Johnsson, and Daniel Burgarth. "Qualitative differences in the robust controllability of model two-qubit systems." European Physical Journal D 80.6 (2026).
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