  An experimental scheme is proposed for building massively multipartite
entangled states using both the spatial and the frequency modes of an optical
parametric oscillator. We provide analytical forms of the entangled states
using the squeezed eigenmodes of Heisenberg equations, a.k.a. the nullifiers of
the corresponding graph state. This scheme can generate, in parallel, several
cluster states described by sparsely connected, bicolorable graph states,
usable for one-way quantum computing. We indicate the experimentally accessible
quantum graphs, depending on the squeezing parameter.
