  Liang information flow is a quantity widely used in classical network theory
to quantify causation, and has been applied widely, for example, to finance and
climate. The most striking aspect here is to freeze/subtract a certain node of
the network to ascertain its causal influence to other nodes of the network.
Such an approach is yet to be applied to quantum network dynamics. Here we
generalize Liang information flow to the quantum domain using the von-Neumann
entropy. Using that we propose to assess the relative importance of various
nodes of a network to causally influence a target node. We exemplify the
application by using small quantum networks.
