Decoherence bypass of macroscopic superpositions in quantum measurement

TL;DR

This paper presents a quantum measurement model where a macroscopic pointer's decoherence is achieved without macroscopic superpositions, by considering initial correlations, simultaneous decoherence processes, and non-Markovian effects.

Contribution

It introduces a comprehensive quantum measurement framework that overcomes previous limitations by incorporating initial correlations, concurrent decoherence, and non-Markovian dynamics.

Findings

Decoherence occurs without macroscopic superpositions.

Initial correlations between pointer and environment are crucial.

Non-Markovian effects influence decoherence dynamics.

Abstract

We study a class of quantum measurement models. A microscopic object is entangled with a macroscopic pointer such that a distinct pointer position is tied to each eigenvalue of the measured object observable. Those different pointer positions mutually decohere under the influence of an environment. Overcoming limitations of previous approaches we (i) cope with initial correlations between pointer and environment by considering them initially in a metastable local thermal equilibrium, (ii) allow for object-pointer entanglement and environment-induced decoherence of distinct pointer readouts to proceed simultaneously, such that mixtures of macroscopically distinct object-pointer product states arise without intervening macroscopic superpositions, and (iii) go beyond the Markovian treatment of decoherence.