  Topological photonic interfaces support topologically non-trivial optical
modes with helical character. When combined with an embedded quantum emitter
that has a circularly polarised transition dipole moment, a chiral quantum
optical interface is formed due to spin-momentum locking. Here, we
experimentally realise such an interface by integrating semiconductor quantum
dots into a valley-Hall topological photonic crystal waveguide. We harness the
robust waveguide transport to create a ring resonator which supports helical
modes. Chiral coupling of quantum dot transitions, with directional contrast as
high as $75\%$, is demonstrated. The interface also supports a topologically
trivial mode, comparison with which allows us to clearly demonstrate the
protection afforded by topology to the non-trivial mode.
