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  • Open Access

Entanglement-breaking channels are a quantum memory resource

Lucas B. Vieira1,2,3,*, Huan-Yu Ku4,†, and Costantino Budroni2,3,5,‡

  • *Contact author: lucas.vieira@tu-darmstadt.de
  • †Contact author: huan.yu@ntnu.edu.tw
  • ‡Contact author: costantino.budroni@unipi.it
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Phys. Rev. Research 7, 043281 – Published 10 December, 2025

DOI: https://doi.org/10.1103/r8lf-bb4p

Abstract

Entanglement-breaking channels (equivalently, measure-and-prepare channels) are quantum operations noted for their ability to destroy multipartite spatial quantum correlations. Inspired by this property, they have also been widely employed in defining notions of “classical memory,” under the assumption that such channels effectively act as a classical resource. In this paper, we show that this assumption is false. By means of multitime correlations, we conclusively show that entanglement-breaking channels are still a quantum resource: A qudit going through an entanglement-breaking channel can generate genuinely nonclassical temporal correlations, i.e., that cannot be simulated by a classical system of same dimension. Our results imply that entanglement-breaking channels cannot generally be employed to characterize classical memory effects without additional assumptions.

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Phys. Rev. Research 7, 043281– Published 10 December, 2025
  • Received 4 March 2024
  • Accepted 22 October 2025
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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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