Violations of Bell's Inequality in Cooperative States

Cooperative multiparticle quantum states in an Einstein-Podolsky-Rosen type of experiment are shown to violate a Bell inequality. Thus correlations can occur between wave packets each having $N$ bosons which cannot be explained within local hidden-variable theories. This provides a way to test quantum measurement theory for multiparticle states. In these states, a local, positive probability distribution exists for all $N$. However, the representation of correlations with this probability distribution is different from that in standard (Bell-type) hidden-variable theories.