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## Summary:

- On decoherence and its relevance for the measurement problem

I'd like to draw attention to the recent survey

- M. Schlosshauer, Quantum decoherence, Physics Reports (2019). Available online 18 October 2019

Maximilian Schlosshauer said:One of the central topics in the foundations of quantum mechanics is known as the quantum measurement problem, and in Sec. 7.1 below we will discuss whether decoherence has anything of substance to say about it. In Sec. 7.2, we will then briefly review the role that decoherence plays, or may play, in the various interpretations of quantum mechanics. In Sec. 7.3, we will comment on Niels Bohr’s views on the primacy of classical concepts and their relationship to the quantum–classical correspondence described by decoherence.

In Section 7.1 said:for the kinds of entangled quantum states produced by decoherence-type interactions to be interpreted as describing a situation in which the system becomes “classical,” we need to take the existence of measurement outcomes as a priori given, or otherwise give an account outside of decoherence of how measurement outcomes are produced, because the property of classicality is ultimately a statement about measurement statistics. Thus decoherence, by itself, cannot address the measurement problem in any substantial way.

Of course, to say that decoherence has no bearing on the measurement problem—or on any of the “big” foundational problems in general—is not to suggest that decoherence and its underlying ideas cannot be of relevance in the investigation of fundamental questions. [...] the ability of decoherence to dynamically define preferred bases is exploited in certain interpretations of quantum mechanics