Broadcast copies reveal the quantumness of correlations

TL;DR

This paper introduces a new measure of quantum correlations based on broadcast copies and mutual information, enabling classification of bipartite states and defining a regularization akin to entanglement measures.

Contribution

It proposes a novel quantification method for quantum correlations using broadcast copies and mutual information, with properties similar to entanglement measures.

Findings

Classifies classical, separable, and entangled states based on broadcast copies.

Defines the broadcast regularization of mutual information with entanglement-like properties.

Demonstrates the measure's effectiveness in capturing quantumness of correlations.

Abstract

We study the quantumness of bipartite correlations by proposing a quantity that combines a measure of total correlations -- mutual information -- with the notion of broadcast copies -- i.e., generally nonfactorized copies -- of bipartite states. By analyzing how our quantity increases with the number of broadcast copies, we are able to classify classical, separable, and entangled states. This motivates the definition of the broadcast regularization of mutual information, the asymptotic minimal mutual information per broadcast copy, which we show to have many properties of an entanglement measure.