Distribution of quantum Fisher information in spin channel

Towards the statistical distinguishability about parameters encoded in the bipartite quantum state, we mainly investigate the distribution and transformation of quantum Fisher information over composite systems in spin channel. The relationship between the global quantum Fisher information and the sum of the locally accessible quantum Fisher information are studied, which can be subadditivity, additivity, or superadditivity. The transfer among them under the unitary operation is illustrated. We find that the quantum Fisher information can not only flow between the reduced systems, but also between the different types of distribution.