  We study the entanglement production in a quantum spin Hall ring geometry
where electrons of opposite spins are emitted in pairs from a source and
collected in two different detectors. Postselection of coincidence detector
events gives rise to entanglement in the system, measurable through
correlations between the outcomes in the detectors. We have chosen a geometry
such that the entanglement depends on the dynamical phases picked up by the
edge states as they move around the ring. In turn, the dependence of the phases
on gate potential and Rashba interaction allows for a precise electrical
control of the entanglement production in the ring.
