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  • Open Access

Emergence of quantum Darwinism and pointer states for noncommuting evolutions

Diana A. Chisholm1,2,*, G. Massimo Palma1, and Luca Innocenti1

  • 1Dipartimento di Fisica e Chimica—Emilio Segrè, Università degli Studi di Palermo, via Archirafi 36, I-90123 Palermo, Italy
  • 2School of Physics, University College Dublin, Belfield Dublin 4, Ireland

  • *Contact author: diana.chisholm@ucd.ie
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APS Open Sci. 1, 000024 – Published 22 May, 2026

DOI: https://doi.org/10.1103/75jr-ltct

Abstract

Quantum systems achieve objectivity by redundantly encoding information about themselves into the surrounding environment, through a mechanism known as quantum Darwinism. When this happens, observers measure the environment and infer the system to be in one of its pointer states. We study the emergence of objectivity whenever the Hamiltonian of the system and the interaction Hamiltonian between system and environment do not commute, a condition where it becomes difficult to identify pointer states, and the use of methods such as the predictability sieve becomes necessary. We show in an explicit qubit model to what degree the noncommuting evolution allows for the emergence of objective states, and show that a definition of pointer states based on spectrum broadcast structure is more natural in this context, and coincides with the one based on the predictability sieve for commuting evolutions.

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APS Open Sci. 1, 000024– Published 22 May, 2026
Vol. 1
  • Received 15 October 2025
  • Accepted 1 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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