High-dimensional topological photonic entanglement

Abstract: The robust generation and manipulation of high-dimensional quantum states lies at the heart of modern quantum computation. The use of topology to resiliently encode and transport quantum information has been widely investigated in condensed matter and has recently penetrated quantum photonics. However, a route to scale up to a large number of entangled topological photonic modes had been missing. Here, we propose and experimentally demonstrate a method to generate high-dimensional topological photonic entanglement. Our platform relies on carefully designed silicon photonic waveguide topological superlattices, which support nonlinear generation of energy-time entangled photon pairs on a superposition of multiple topological modes. Our measurements and theoretical analysis reveal entanglement of up to five topological modes with resilience to nanofabrication imperfections. This study, at the intersection of nonlinear integrated photonics, quantum information, and topology, opens a research avenue toward scalable, fault-tolerant quantum photonic states.