  We propose to use the quantum Fisher information in characterizing the
information flow of open quantum systems. This information-theoretic approach
provides a quantitative measure to statistically distinguish Markovian and
non-Markovian processes. A basic relation between the QFI flow and
non-Markovianity is unveiled for quantum dynamics of open systems. For a class
of time-local master equations, the exactly-analytic solution shows that the
non-Markovianity is characterized by additive information sub-flows in
different non-Markovian channels.
