Parametric description of the quantum measurement process

TL;DR

This paper introduces a parametric framework for quantum measurement that incorporates environmental states, explaining how measurement outcomes emerge from symmetry breaking and the macroscopic nature of measuring devices.

Contribution

It develops a novel parametric representation for quantum measurements that captures the quantum-to-classical transition and explains outcome production via symmetry breaking.

Findings

Measurement outcome results from global-symmetry breaking.

The statistical nature and Born's rule arise from the macroscopic properties of the apparatus.

The approach extends beyond the pre-measurement stage to describe outcome formation.

Abstract

We present a description of the measurement process based on the parametric representation with environmental coherent states. This representation is specifically tailored for studying quantum systems whose environment needs being considered through the quantum-to-classical cross-over. Focusing upon projective measures, and exploiting the connection between large-$N$ quantum theories and the classical limit of related ones, we manage to push our description beyond the pre-measurement step. This allows us to show that the outcome production follows from a global-symmetry breaking, entailing the observed system's state reduction, and that the statistical nature of the process is brought about, together with the Born's rule, by the macroscopic character of the measuring apparatus.