  Among the various kinds of entangled states, the 'W state' plays an important
role as its entanglement is maximally persistent and robust even under particle
loss. Such states are central as a resource in quantum information processing
and multiparty quantum communication. Here we report the scalable and
deterministic generation of four-, five-, six-, seven- and eight-particle
entangled states of the W type with trapped ions. We obtain the maximum
possible information on these states by performing full characterization via
state tomography, using individual control and detection of the ions. A
detailed analysis proves that the entanglement is genuine. The availability of
such multiparticle entangled states, together with full information in the form
of their density matrices, creates a test-bed for theoretical studies of
multiparticle entanglement. Independently, -Greenberger-Horne-Zeilinger-
entangled states with up to six ions have been created and analysed in Boulder.
