Generalized Observables, Bell's Inequalities and Mixtures in the ESR Model for QM

TL;DR

The ESR model reinterprets quantum probabilities within a noncontextual framework, generalizes observables and the projection postulate, and offers new insights into Bell inequalities and the representation of mixtures in quantum mechanics.

Contribution

It introduces a new mathematical framework for observables and mixtures in the ESR model, extending quantum theory and addressing foundational issues.

Findings

Bell-CHSH inequalities are compatible with the ESR model.

A new representation of mixtures avoids problems of standard QM.

Generalized Luders postulate is justified under specific conditions.

Abstract

The extended semantic realism (ESR) model proposes a new theoretical perspective which embodies the mathematical formalism of standard (Hilbert space) quantum mechanics (QM) into a noncontextual framework, reinterpreting quantum probabilities as conditional instead of absolute. We provide in this review an overall view on the present status of our research on this topic. We attain in a new, shortened way a mathematical representation of the generalized observables introduced by the ESR model and a generalization of the projection postulate of elementary QM. Basing on these results we prove that the Bell-Clauser-Horne-Shimony-Holt (BCHSH) inequality, a modified BCHSH inequality and quantum predictions hold together in the ESR model because they refer to different parts of the picture of the physical world supplied by the model. Then we show that a new mathematical representation of mixtures must be introduced in the ESR model which does not coincide with the standard representation in QM and avoids some deep problems that arise from the representation of mixtures provided by QM. Finally we get a nontrivial generalization of the Luders postulate, which is justified in a special case by introducing a reasonable physical assumption on the evolution of the compound system made up of the measured system and the measuring apparatus.