Informationally coherent quantum systems

An information-theoretic approach to correlated quantum systems is developed. The precise definitions of the informationally coherent N-component system are presented in terms of the state (observable) dependent index of correlation. The informational coherence of the N-particle GHZ system in an entangled pure state is analysed and it is found that the observable-dependent index of correlation is less than or equal to the state-dependent one divided by N. It is pointed out that the informationally coherent quantumsystems violate the Bell theorem.