Observers and Locality in Everett Quantum Field Theory

TL;DR

This paper introduces a local, measurement-compatible model in Everett quantum field theory that explicitly includes observers and demonstrates local calculations of quantum phenomena, including EPR correlations.

Contribution

It extends previous models by incorporating explicit localized observers and establishing locality through transformations, enabling local analysis of measurement and entanglement.

Findings

Successfully models measurement with localized observers in Everett quantum field theory.

Demonstrates local calculation of EPR spin correlations.

Provides a nonperturbative computational framework for quantum measurement phenomena.

Abstract

A model for measurement in collapse-free nonrelativistic fermionic quantum field theory is presented. In addition to local propagation and effectively-local interactions, the model incorporates explicit representations of localized observers, thus extending an earlier model of entanglement generation in Everett quantum field theory [M. A. Rubin, Found. Phys. 32, 1495-1523 (2002)]. Transformations of the field operators from the Heisenberg picture to the Deutsch-Hayden picture, involving fictitious auxiliary fields, establish the locality of the model. The model is applied to manifestly-local calculations of the results of measurements, using a type of sudden approximation and in the limit of massive systems in narrow-wavepacket states. Detection of the presence of a spin-1/2 system in a given spin state by a freely-moving two-state observer illustrates the features of the model and the nonperturbative computational methodology. With the help of perturbation theory the model is applied to a calculation of the quintessential "nonlocal" quantum phenomenon, spin correlations in the Einstein-Podolsky-Rosen-Bohm experiment.