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arXiv · 2508.16482

Decoherent histories with(out) objectivity in a (broken) apparatus

Benoît Ferté·Davide Farci·Xiangyu Cao
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Abstract

We characterize monitored quantum dynamics in a solvable model exhibiting a phase transition between a measurement apparatus and a scrambler. We show that approximate decoherent histories emerge in both phases with respect to a coarse-grained extensive observable. However, the apparatus phase, where quantum Darwinism emerges, is distinguished by the non-ergodicity of the histories and their correlation with the measured qubit, which selects an ensemble of preferred pointer states. Our results demonstrate a clear distinction between two notions of classicality, decoherent histories and environment-induced decoherence.

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Benoît Ferté, Davide Farci, Xiangyu Cao. 2025-08-22. Decoherent histories with(out) objectivity in a (broken) apparatus. https://doi.org/10.1103/8qzx-xpfz

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