  The cluster states and Greenberger-Horne-Zeilinger (GHZ) states are two
different types of multipartite quantum entangled states. We present the first
experimental results generating continuous variable quadripartite cluster and
GHZ entangled states of electromagnetic fields. Utilizing four two-mode
squeezed states of light and linearly optical transformations, the two types of
entangled states for amplitude and phase quadratures of light are
experimentally produced. The combinations of the measured quadrature variances
prove the full inseparability of the generated four subsystems. The presented
experimental schemes show that the multipartite entanglement of continuous
variables can be deterministically generated with the relatively simple
implementation.
