Locality and Classicality: role of entropic inequalities

TL;DR

This paper investigates the relationship between classicality and nonlocality in multiqubit quantum systems using entropic inequalities, revealing deep connections among various quantum correlation measures.

Contribution

It introduces the concept of classicality based on entropic inequalities and compares it with nonlocality, analyzing their relationship across different multiqubit states.

Findings

Classicality and nonlocality are deeply connected despite their different natures.

Quantum correlation measures show surprising relationships when analyzed through entropic inequalities.

The study extends to systems with arbitrary numbers of qubits, considering their degree of mixture.

Abstract

The use of the so-called entropic inequalities is revisited in the light of new quantum correlation measures, specially nonlocality. We introduce the concept of {\it classicality} as the non-violation of these classical inequalities by quantum states of several multiqubit systems and compare it with the non-violation of Bell inequalities, that is, {\it locality}. We explore --numerically and analytically-- the relationship between several other quantum measures and discover the deep connection existing between them. The results are surprising due to the fact that these measures are very different in their nature and application. The cases for $n=2,3,4$ qubits and a generalization to systems with arbitrary number of qubits are studied here when discriminated according to their degree of mixture.