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  • Open Access

Verifiable end-to-end delegated variational quantum algorithms

Matteo Inajetovic1,*, Petros Wallden2, and Anna Pappa1

  • *Contact author: m.inajetovic@tu-berlin.de
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Phys. Rev. Research 8, 033043 – Published 10 July, 2026

DOI: https://doi.org/10.1103/9yqy-8ch9

Abstract

Variational quantum algorithms (VQAs) have emerged as promising candidates for solving complex optimization and machine learning tasks on near-term quantum hardware. However, executing quantum operations remains challenging for small-scale users because of several hardware constraints, making it desirable to delegate parts of the computation to more powerful quantum devices. In this work, we introduce a framework for delegated variational quantum algorithms, where a client with limited quantum capabilities delegates the execution of a VQA to a more powerful quantum server. In particular, we introduce a protocol that enables a client to delegate a variational quantum algorithm to a server while ensuring that the input, the output, and also the computation itself remain secret. Additionally, if the protocol does not abort, the client can be certain that the computation outcome is indeed correct. This work builds on the general verification protocol introduced by Fitzsimons and Kashefi [Phys. Rev. A 96, 012303 (2017)], tailoring it to VQAs. Our approach first proposes a verifiable protocol for delegating the quantum computation at each optimization step of a VQA and then combines the iterative steps into an error-resilient optimization process that offers end-to-end verifiable algorithm execution. We also simulate the performance of our protocol tackling the transverse field Ising model. Our results demonstrate that secure delegation of variational quantum algorithms is a realistic solution for near-term quantum networks, paving the way for practical quantum cloud computing applications.

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Phys. Rev. Research 8, 033043– Published 10 July, 2026
  • Received 2 July 2025
  • Accepted 9 May 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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