On a generalized peaceful coexistence of special relativity and quantum mechanics

The result that quantum nonlocality is causal because it cannot be used to transfer classical information across spacelike intervals is extended to entangled n-partite systems (n greater than or equal to 2). We show that correlations between any m (0 < m < n) of the subsystems is independent of unitary operations performed on any other k subsystems and/or (projective, nondegenerate) measurement operations performed on any other l (n - m less than or equal to l, k < n) subsystems. This corroborates the peaceful coexistence of quantum mechanics and special relativity, and is in keeping with the understanding that the total information in an entangled system is locally inaccessible. (C) 2001 Elsevier Science B.V. All rights reserved.