Controlling Collective Quasiparticle Dynamics Beyond Decoherence in Topological Interfaces

Photonic environments with engineered chirality offer a practical route to coherence control at the nanoscale. We demonstrate that a symmetry‐broken plasmonic honeycomb lattice functions as a directional reservoir that preserves emitter coherence even in the weak‐coupling regime. Using a coupled‐dipole model linked to cascaded‐Lindblad dynamics, we find that spin‐momentum‐locked edge modes mediate unidirectional energy transfer and produce subradiant and superradiant dynamics over mesoscopic distances. Far‐field polarization maps (Stokes S 3 ) directly trace this phase preservation, while time‐domain simulations reveal sustained collective oscillations beyond the near field. Together, these results establish a design framework for chiral plasmonic interfaces that support coherence‐protected light‐matter interactions, providing an experimentally accessible path toward phase‐stable quantum photonic functionality at ambient conditions.