Direct Measure of Quantum Correlation

TL;DR

This paper introduces a new direct measure of quantum correlation that captures the structural differences between classical and quantum states, offering a unified and computationally accessible approach.

Contribution

It proposes a novel direct measure of quantum correlation based on state structure differences, improving understanding and computation over existing quantum discord measures.

Findings

The measure explicitly accounts for inseparability and local non-orthogonality.

It provides a unified framework for various quantum correlation measures.

The measure is relatively easy to compute.

Abstract

The quantumness of the correlation known as quantum correlation is usually measured by quantum discord. So far various quantum discords can be roughly understood as indirect measure by some special discrepancy of two quantities. We present a direct measure of quantum correlation by revealing the difference between the structures of classically and quantum correlated states. Our measure explicitly includes the contributions of the inseparability and local non-orthogonality of the eigenvectors of a density. Besides its relatively easy computability, our measure can provide a unified understanding of quantum correlation of all the present versions.