Four questions for quantum-classical hybrid theory

TL;DR

This paper examines a recent linear quantum-classical hybrid theory, addressing its consistency, ability to handle quantum states, locality, and implications for the emergence of quantum mechanics.

Contribution

It analyzes a specific hybrid dynamics proposal, evaluating its foundational properties and potential to explain quantum phenomena from underlying dynamics.

Findings

The hybrid theory fulfills key consistency requirements.

It can represent superposition, separable, and entangled states.

Questions remain about locality and emergence of quantum mechanics.

Abstract

Four questions are discussed which may be addressed to any proposal of a quantum-classical hybrid theory which concerns the direct coupling of classical and quantum mechanical degrees of freedom. In particular, we consider the formulation of hybrid dynamics presented recently in Ref.[1]. This linear theory differs from the nonlinear ensemble theory of Hall and Reginatto, but shares with it to fulfil all consistency requirements discussed in the literature, while earlier attempts failed. - Here, we additionally ask: Does the theory allow for superposition, separable, and entangled states originating in the quantum mechanical sector? Does it allow for "Free Will", as introduced, in this context, by Diosi [2]. Is it local? Does it provide hints for the emergence of quantum mechanics from dynamics beneath?