How to construct entanglement witnesses

TL;DR

This paper introduces a straightforward method for constructing entanglement witnesses, capable of detecting weak quantum entanglement and bound entangled states, especially effective in multipartite systems.

Contribution

The authors propose a novel, simple approach to generate indecomposable entanglement witnesses from existing pairs, enhancing detection of weak and bound entanglement.

Findings

Effective in multipartite systems

Able to detect weak entanglement

Facilitates construction of bound entangled states

Abstract

We present very simple method for constructing indecomposable entanglement witnesses out of a given pair -- an entanglement witness W and the corresponding state detected by W. This method may be used to produce new classes of atomic witnesses which are able to detect the `weakest' quantum entanglement. Actually, it works perfectly in the multipartite case, too. Moreover, this method provides a powerful tool for constructing new examples of bound entangled states.