Experimental construction of optical multiqubit cluster states from Bell states

Cluster states serve as the central physical resource for one-way quantum computing. We here present an experimental demonstration of the efficient cluster-state construction scheme proposed by Browne and Rudolph. In our experiment, three-photon cluster states with high purity are created from two Bell states via a qubit fusion operation, showing a strong violation of a three-particle Mermin inequality of vertical bar < A >vertical bar=3.10 +/- 0.03. In addition, the entanglement properties of the cluster states are examined under sigma(z) and sigma(x) measurements on a qubit. This scheme could be extended to any desired number of qubits and represents an essential step for the optical one-way quantum computation.