Experimental violation of a cluster state Bell inequality

Author(s): P. Walther, M. Aspelmeyer, K. J. Resch, A. Zeilinger

Journal: Physical Review Letters

Volume: 95

Page(s): 020403

Year: 2005

DOI Number: 10.1103/PhysRevLett.95.020403

Link: Link to publication


Cluster states are a new type of multiqubit entangled states with entanglement properties exceptionally well suited for quantum computation. In the present work, we experimentally demonstrate that correlations in a four-qubit linear cluster state cannot be described by local realism. This exploration is based on a recently derived Bell-type inequality [V. Scarani et al., Phys. Rev. A 71 042325 (2005)] which is tailored, by using a combination of three- and four-particle correlations, to be maximally violated by cluster states but not violated at all by GHZ states. We observe a cluster-state Bell parameter of 2.59±0.08, which is more than 7σ larger than the threshold of 2 imposed by local realism.

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Aspelmeyer Group Aspelmeyer Group , Walther Group , Zeilinger Group