Greenberger–Horne–Zeilinger states: Their identifications and robust violations

The $N$-qubit Greenberger-Horne-Zeilinger (GHZ) states are the maximally entangled of $N$ qubits, which have had many important applications in quantum information processing, such as key distribution and secret sharing. Thus how to distinguish GHZ from other becomes a significant problem. In this work, by presenting family generalized Clauser-Horne-Shimony-Holt (CHSH) inequality, we show that can be indeed identified maximal violations CHSH inequality under some specific measurement settings. is simple contains only four correlation functions for any system, thus has merit facilitating experimental verification. Furthermore, present phenomenon robust violation Bell's noises adding states.