Detecting genuine multipartite entanglement with two local measurements

Phys Rev Lett. 2005 Feb 18;94(6):060501. doi: 10.1103/PhysRevLett.94.060501. Epub 2005 Feb 17.


We present entanglement witness operators for detecting genuine multipartite entanglement. These witnesses are robust against noise and require only two local measurement settings when used in an experiment, independent of the number of qubits. This allows detection of entanglement for an increasing number of parties without a corresponding increase in effort. The witnesses presented detect states close to Greenberger-Horne-Zeilinger, cluster, and graph states. Connections to Bell inequalities are also discussed.