  The cluster state, the highly entangled state that is the central resource
for one-way quantum computing, can be efficiently generated in a variety of
physical implementations via global nearest-neighbor interactions. In practice,
a systematic phase error is expected in the entangling process, resulting in
imperfect cluster states. We present a stochastic measurement technique to
generate large perfect cluster states and other graph states with high
probability from imperfect cluster states even when their initial entanglement
is weak.
