title: Comment on "Multipartite entanglement among single spins in diamond".
abstract: Neumann et al. (Reports, 6 June 2008, p. 1326) recently reported the preparation of multiparticle entanglement among single spins in diamond. However, two of the system's nuclear eigenstates are incorrectly described as product states when they are inherently entangled. Consequently, three of the six states reported, namely the odd-parity Bell states and the W state, were not actually produced.
authors.affiliation: Department of Materials, Oxford University, Oxford OX1 3PH, UK. brendon.lovett@materials.ox.ac.uk
authors.forename: Brendon W
authors.initials: BW
authors.lastname: Lovett
authors.forename: Simon C
authors.initials: SC
authors.lastname: Benjamin