  We investigate a variant of the SSH model consisting of an SSH chain with an
embedded Aharonov-Bohm quantum ring. The embedded ring gives rise to domain
wall states whose energy levels are in the band gap. The dependence of some of
the states on the ring's magnetic flux provides a mechanism to control the
entanglement between the two SSH edge fermion modes. The concurrence between
the edge modes depends periodically on the magnetic flux. In the deep
topological zone, for appropriate values of the flux, the concurrence reaches
the extreme values of $0$ and $1$, corresponding to vanishing entanglement and
to maximum entanglement. Therefore, the QR-SSH system offers a tuning mechanism
that can be used either as an entanglement modulator or as an entanglement
switch.

Other Condensed Matter;Quantum Physics