Compact and reconfigurable silicon nitride time-bin entanglement circuit

Photonic-chip-based time-bin entanglement has attracted significant attention because of its potential for quantum communication and computation. Useful time-bin entanglement systems must be able to generate, manipulate, and analyze entangled photons on a photonic chip for stable, scalable, and reconfigurable operation. Here we report the first time-bin entanglement photonic chip that integrates pump time-bin preparation, wavelength demultiplexing, and entanglement analysis. A two-photon interference fringe with 88.4% visibility is measured (without subtracting any noise), indicating the high performance of the chip. Our approach, based on a silicon nitride photonic circuit, which combines low loss and tight integration features, paves the way for scalable real-world quantum information processors.