Correlation function and mutual information

TL;DR

This paper compares correlation function and mutual information in quantum states, revealing they can lead to different assessments of correlation orderings, highlighting the measure-dependent nature of quantum correlations.

Contribution

It demonstrates that correlation function and mutual information can produce different correlation orderings in quantum states, emphasizing the importance of measure choice.

Findings

Correlation function and mutual information may yield different correlation orderings.

The measure-dependent nature of quantum correlation assessments is highlighted.

Different tools can lead to contrasting conclusions about quantum state correlations.

Abstract

Correlation function and mutual information are two powerful tools to characterize the correlations in a quantum state of a composite system, widely used in many-body physics and in quantum information science, respectively. We find that these two tools may give different conclusions about the order of the degrees of correlation in two specific two-qubit states. This result implies that the orderings of bipartite quantum states according to the degrees of correlation depend on which correlation measure we adopt.