Quasi-quantization: classical statistical theories with an epistemic restriction

TL;DR

This paper explores how a fundamental epistemic restriction on classical statistical theories can produce quantum-like phenomena, unifying various epistricted theories through classical complementarity and proposing a classification of quantum phenomena based on their classical simulability.

Contribution

It introduces a unifying epistemic restriction called classical complementarity and presents a quasi-quantization scheme applicable to classical degrees of freedom.

Findings

Classical complementarity unifies known epistricted theories.

The restriction applies to continuous and discrete degrees of freedom.

Proposes a classification of quantum phenomena as weakly or strongly nonclassical.

Abstract

A significant part of quantum theory can be obtained from a single innovation relative to classical theories, namely, that there is a fundamental restriction on the sorts of statistical distributions over physical states that can be prepared. This is termed an "epistemic restriction" because it implies a fundamental limit on the amount of knowledge that any observer can have about the physical state of a classical system. This article provides an overview of epistricted theories, that is, theories that start from a classical statistical theory and apply an epistemic restriction. We consider both continuous and discrete degrees of freedom, and show that a particular epistemic restriction called classical complementarity provides the beginning of a unification of all known epistricted theories. This restriction appeals to the symplectic structure of the underlying classical theory and consequently can be applied to an arbitrary classical degree of freedom. As such, it can be considered as a kind of quasi-quantization scheme; "quasi" because it generally only yields a theory describing a subset of the preparations, transformations and measurements allowed in the full quantum theory for that degree of freedom, and because in some cases, such as for binary variables, it yields a theory that is a distortion of such a subset. Finally, we propose to classify quantum phenomena as weakly or strongly nonclassical by whether or not they can arise in an epistricted theory.