Chiral Quantum Optics With Topological Photonic Crystal Waveguide of Triangular Lattice

ABSTRACT We present a versatile dielectric platform for studying chiral light–matter interaction and cavity quantum electrodynamics, based on high bend transmittance waveguide (HBT WG) modes of triangular‐lattice photonic crystals (Tri‐PhCs). The demonstration of chiral coupling is realized by employing two Tri‐PhC zigzag interface waveguides which offer a simplified geometry in the first place. Compared to previous honeycomb‐lattice systems, Tri‐PhC zigzag waveguides provide at least twice the effective chiral area for quantum dot (QD) interaction and support accessible slow‐light modes that are crucial for light–matter interaction. Integrating self‐assembled QDs, we experimentally demonstrate chiral photon routing in Z‐shaped Tri‐PhC HBT WGs, confirming robust directional photon transport. Additionally, we incorporate a whispering‐gallery‐mode cavity‐waveguide structure to achieve Purcell‐enhanced on‐chip single‐photon emission, with a Purcell factor of 4 and spin‐dependent directional contrast of 82%. Our results show the potential of Tri‐PhC‐based topological waveguides as a promising, scalable platform for low‐loss, high‐chirality quantum photonic devices.