Paper detail

Irreducible multiparty correlation can be created by local operations

Generalizing Amari's work titled "Information geometry on hierarchy of probability distributions", we define the degrees of irreducible multiparty correlations in a multiparty quantum state based on quantum relative entropy. We prove that these definitions are equivalent to those derived from the maximal von Neaumann entropy principle. Based on these definitions, we find a counterintuitive result on irreducible multiparty correlations: although the degree of the total correlation in a three-party quantum state does not increase under local operations, the irreducible three-party correlation can be created by local operations from a three-party state with only irreducible two-party correlations. In other words, even if a three-party state is initially completely determined by measuring two-party Hermitian operators, the determination of the state after local operations have to resort to the measurements of three-party Hermitian operators.