Chiral topological photonics with an embedded quantum emitter

Topological photonic interfaces support topologically nontrivial optical modes with helical character. When combined with an embedded quantum emitter that has a circularly polarized transition dipole moment, a chiral quantum optical interface is formed due to spin-momentum locking. Here, we experimentally realize 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 that 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 nontrivial mode. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License.