Quantitative bounds to propagation of quantum correlations in many-body systems

TL;DR

This paper establishes quantitative limits on how much quantum information can be shared among many-body systems, showing that classical information proliferation suppresses quantum correlations.

Contribution

It generalizes previous bounds on quantum discord and entanglement, providing universal limits on quantum correlations in many-body systems.

Findings

Bounds on quantum discord quantify deviation from classical states.

Universal upper bound on bipartite entanglement of formation.

Proliferation of classical information suppresses quantum correlations.

Abstract

We investigate how much information about a quantum system can be simultaneously communicated to independent observers, by establishing quantitative limits to bipartite quantum correlations in many-body systems. As recently reported in Phys. Rev. Lett. 129, 010401 (2022), bounds on quantum discord and entanglement of formation between a single quantum system and its environment, e.g., a large number of photons, dictate that independent observers which monitor environment fragments inevitably acquire only classical information about the system. Here, we corroborate and generalize those findings. First, we calculate continuity bounds of quantum discord, which establish how much states with a small amount of quantum correlations deviate from being embeddings of classical probability distributions. Also, we demonstrate a universally valid upper bound to the bipartite entanglement of formation between an arbitrary pair of components of a many-body quantum system. The results confirm that proliferation of classical information in the Universe suppresses quantum correlations.