Detecting Genuine Multipartite Entanglement with Two Local Measurements

Abstract

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 from 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 GHZ, cluster and graph states. Connections to Bell inequalities are also discussed.

4 pages including 1 figure, revtex4; changes before publication in PRL; discussion about Mermin's inequality added in Ref. 22