Harmony for 2-Qubit Entanglement

TL;DR

This paper introduces 'harmony,' a new, easily computable measure of entanglement for two-qubit systems that captures separability and maximal entanglement, and is monogamous for three-qubit states.

Contribution

It proposes a novel entanglement measure called harmony, which is simple to compute and applicable to general qubit systems, enhancing entanglement analysis.

Findings

Harmony indicates entanglement status effectively.

Harmony is monogamous for 3-qubit states.

It is easier to compute than existing measures.

Abstract

In this Letter we present a new quantity that shows whether two general qubit systems are entangled, which we call harmony. It captures the notion of separability and maximal entanglement. It is also shown that harmony is monogamous for 3-qubit states. Thus, harmony serves as a new entanglement measure. In addition, since it is written as a simple function of the density operator, it is in practice easier to compute than other previously known measures.