  We use an entanglement measure that respects the superselection of particle
number to study the non-local properties of symmetry-protected topological edge
states. Considering half-filled M-leg Su-Schrieffer-Heeger (SSH) ladders as an
example, we show that the topological properties and the operational
entanglement extractable from the boundaries are intimately connected.
Topological phases with at least two filled edge states have the potential to
realize genuine, non-bipartite, many-body entanglement which can be transferred
to a quantum register. The entanglement is extractable when the filled edge
states are sufficiently localized on the lattice sites controlled by the users.
We show, furthermore, that the onset of entanglement between the edges can be
inferred from local particle number spectroscopy alone and present an
experimental protocol to study the breaking of Bell's inequality.
