QMetro++ – Python optimization package for large scale quantum metrology with customized strategy structures

Piotr Dulian; Stanisław Kurdziałek; Rafał Demkowicz-Dobrzański

doi:10.22331/q-2026-01-29-1991

QMetro++ – Python optimization package for large scale quantum metrology with customized strategy structures

Piotr Dulian^1,2, Stanisław Kurdziałek², and Rafał Demkowicz-Dobrzański²

¹Centre for Quantum Optical Technologies, Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warszawa, Poland
²Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warszawa, Poland

Published:	2026-01-29, volume 10, page 1991
Editor:	Mark Mitchison
Eprint:	arXiv:2506.16524v3
Doi:	https://doi.org/10.22331/q-2026-01-29-1991
Citation:	Quantum 10, 1991 (2026).

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Abstract

QMetro++ is a Python package that provides a set of tools for identifying optimal estimation protocols that maximize quantum Fisher information (QFI). Optimization can be performed for arbitrary configurations of input states, parameter-encoding channels, noise correlations, control operations, and measurements. The use of tensor networks and an iterative see-saw algorithm allows for an efficient optimization even in the regime of a large number of channel uses ($N\approx100$). Additionally, the package includes implementations of the recently developed methods for computing fundamental upper bounds on QFI, which serve as benchmarks for assessing the optimality of numerical optimization results. All functionalities are wrapped up in a user-friendly interface which enables the definition of strategies at various levels of detail.

QMetro++ – Python optimization package for large scale quantum metrology with customized strategy structures at Github

► BibTeX data

@article{Dulian2026qmetropython,
  doi = {10.22331/q-2026-01-29-1991},
  url = {https://doi.org/10.22331/q-2026-01-29-1991},
  title = {{QM}etro++ – {P}ython optimization package for large scale quantum metrology with customized strategy structures},
  author = {Dulian, Piotr and Kurdzia{\l{}}ek, Stanis{\l{}}aw and Demkowicz-Dobrza{\'{n}}ski, Rafa{\l{}}},
  journal = {{Quantum}},
  issn = {2521-327X},
  publisher = {{Verein zur F{\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}},
  volume = {10},
  pages = {1991},
  month = jan,
  year = {2026}
}

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Cited by

[1] Arpan Das and Rafał Demkowicz-Dobrzański, "Quantum metrology in the presence of correlated noise via Markovian embedding", Physical Review A 113 2, 022418 (2026).

[2] Árpád Lukács, Róbert Trényi, Tamás Vértesi, and Géza Tóth, "Iterative optimization in quantum metrology and entanglement theory using semidefinite programming", Quantum Science and Technology 11 1, 015042 (2026).

[3] Gabriela Wójtowicz, Susana F. Huelga, Marek M. Rams, and Martin B. Plenio, "Quantum Fisher information from tensor-network integration of the Lyapunov equation", Physical Review A 112 5, 052454 (2025).

[4] Stanisław Kurzyna, Bartosz Niewelt, Mateusz Mazelanik, Wojciech Wasilewski, Rafał Demkowicz-Dobrzański, and Michał Parniak, "Microwave-field quantum metrology with inherent robustness against detection losses enabled by Rydberg interactions", arXiv:2505.01506, (2025).

[5] Zixin Huang, Johannes Jakob Meyer, Theshani Nuradha, and Mark M. Wilde, "Query complexities of quantum channel discrimination and estimation: A unified approach", arXiv:2511.10832, (2025).

[6] Stanisław Sieniawski and Rafał Demkowicz-Dobrzański, "Adaptive quantum channel discrimination using methods of quantum metrology", arXiv:2510.15506, (2025).

[7] Michal Arieli, Alex Retzker, and Tuvia Gefen, "Optimal quantum metrology protocols with erasure qubits", arXiv:2603.11807, (2026).

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