Computable Measure of Total Quantum Correlation of Multipartite Systems

TL;DR

This paper introduces a new, easily computable measure of total quantum correlations in multipartite systems, capable of detecting quantum critical points and applicable to complex mixed states.

Contribution

It proposes a novel operational measure based on coherence vectors and correlation matrices, improving computability over traditional quantum discord measures.

Findings

Effective detection of quantum critical points in spin chains

Applicable to arbitrary mixed multipartite states

Simplifies quantification of quantum correlations

Abstract

Quantum discord as a measure of the quantum correlations cannot be easily computed for most of density operators. In this paper, we present a measure of the total quantum correlations that is operationally simple and can be computed effectively for an arbitrary mixed state of a multipartite system. The measure is based on the coherence vector of the party whose quantumness is investigated as well as the correlation matrix of this part with the remainder of the system. Being able to detect the quantumness of multipartite systems, such as detecting the quantum critical points in spin chains, alongside with the computability characteristic of the measure, make it a useful indicator to be exploited in the cases which are out of the scope of the other known measures.