Quantifying quantum discord and entanglement of formation via unified purifications

TL;DR

This paper introduces a unified scheme to analytically quantify quantum discord and entanglement of formation in mixed states, revealing their relationship and enabling analysis of quantum correlations under decoherence.

Contribution

It presents a novel analytical method to evaluate quantum discord and entanglement of formation using purification, applicable to specific quantum states and their dynamics.

Findings

Analytical expressions for quantum discord and entanglement of formation derived.

Established an intrinsic relationship between quantum discord and entanglement.

Characterized the dynamical behavior of quantum correlations under decoherence.

Abstract

We propose a scheme to evaluate the amount of quantum discord and entanglement of formation for mixed states, and reveal their ordering relation via an intrinsic relationship between the two quantities distributed in different partners of the associated purification. This approach enables us to achieve analytical expressions of the two measures for a sort of quantum states, such as an arbitrary two-qubit density matrix reduced from pure three-qubit states and a class of rank-2 mixed states of 4\times 2 systems. Moreover, we apply the scheme to characterize fully the dynamical behavior of quantum correlations for the specified physical systems under decoherence.