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Quantum nonlocality of four-qubit entangled states

Chunfeng Wu·Ye Yeo·L. C. Kwek·C. H. Oh
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Abstract

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 $|\chi>$ that has been recently proposed in [PRL, {\bf 96}, 060502 (2006)]. The Bell inequality is optimally violated by $|\chi>$ but not violated by the GHZ state. The cluster state also violates the Bell inequality though not optimally. The state $|\chi>$ 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)].

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Chunfeng Wu, Ye Yeo, L. C. Kwek, C. H. Oh. 2006-11-16. Quantum nonlocality of four-qubit entangled states. https://doi.org/10.1103/physreva.75.032332

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