Redundantly amplified information suppresses quantum correlations in many-body systems

TL;DR

This paper demonstrates that quantum correlations in many-body systems are suppressed by redundant information amplification, supporting the idea that classical objectivity emerges naturally from quantum mechanics through Quantum Darwinism.

Contribution

It establishes bounds on quantum correlations related to environment monitoring, showing how classical information emerges without postulating objective reality.

Findings

Classical objectivity arises from redundant information dissemination.

Bounds on quantum correlations restrict how much environment fragments can share about the system.

Emergence of classicality is signaled by specific scaling of mutual information.

Abstract

We establish bounds on quantum correlations in many-body systems. They reveal what sort of information about a quantum system can be simultaneously recorded in different parts of its environment. Specifically, independent agents who monitor environment fragments can eavesdrop only on amplified and redundantly disseminated - hence, effectively classical - information about the decoherence-resistant pointer observable. We also show that the emergence of classical objectivity is signaled by a distinctive scaling of the conditional mutual information, bypassing hard numerical optimizations. Our results validate the core idea of Quantum Darwinism: objective classical reality does not need to be postulated and is not accidental, but rather a compelling emergent feature of quantum theory that otherwise - in absence of decoherence and amplification - leads to "quantum weirdness". In particular, a lack of consensus between agents that access environment fragments is bounded by the information deficit, a measure of the incompleteness of the information about the system.