Topological Floquet integrated photonics for entanglement generation

Current integrated implementations of entangled photonic sources are limited by fabrication imperfections and defects that introduce scattering and loss, degrading entanglement quality. Topological photonic insulators have recently emerged as a promising platform for robust photon transport due to their resilience against defect-induced scattering, enabling disorder-tolerant entangled photon generation. However, realizing bright entangled sources in topological systems remains challenging because of weak material optical nonlinearities. Here, we demonstrate entangled photon-pair generation in a nonmagnetic and wavelength-tunable anomalous Floquet topological insulator using spontaneous four-wave mixing. Time-energy entanglement is verified through photon coincidence measurements.