When are quantum systems operationally independent?

TL;DR

This paper explores the concept of operational independence in quantum systems, proposing formulations and clarifying its relation to existing concepts, demonstrating its general applicability in various quantum theories.

Contribution

It introduces new formulations of operational independence and explains its broad validity across different quantum frameworks.

Findings

Operational independence holds generally in quantum systems.

The paper clarifies the relation between operational independence and other independence concepts.

It applies to both nonrelativistic and relativistic quantum theories.

Abstract

We propose some formulations of the notion of "operational independence" of two subsystems of a larger quantum system and clarify their relation to other independence concepts in the literature. In addition, we indicate why the operational independence of quantum subsystems holds quite generally, both in nonrelativistic and relativistic quantum theory.