  We investigate entanglement dynamics in multipartite systems, establishing a
quantitative concept of entanglement flow: both flow through individual
particles, and flow along general networks of interacting particles. In the
former case, the rate at which a particle can transmit entanglement is shown to
depend on that particle's entanglement with the rest of the system. In the
latter, we derive a set of entanglement rate equations, relating the rate of
entanglement generation between two subsets of particles to the entanglement
already present further back along the network. We use the rate equations to
derive a lower bound on entanglement generation in qubit chains, and compare
this to existing entanglement creation protocols.
