Quantum nonlocality of several four-qubit states is investigated by constructing a new Bell inequality. These include the Greenberger-Zeilinger-Horne (GHZ) state, W state, cluster state, and the state ∣χ> that has been recently proposed in [PRL, {\bf 96}, 060502 (2006)]. The Bell inequality is optimally violated by ∣χ> but not violated by the GHZ state. The cluster state also violates the Bell inequality though not optimally. The state ∣χ> can thus be discriminated from the cluster state by using the inequality. Different aspects of four-partite entanglement are also studied by considering the usefulness of a family of four-qubit mixed states as resources for two-qubit teleportation. Our results generalize those in [PRL, {\bf 72}, 797 (1994)].
@article{arxiv.quant-ph/0611172,
title = {Quantum nonlocality of four-qubit entangled states},
author = {Chunfeng Wu and Ye Yeo and L. C. Kwek and C. H. Oh},
journal= {arXiv preprint arXiv:quant-ph/0611172},
year = {2013}
}