Phys.org February 8, 2023 The large-photon-number quantum state is a fundamental but nonresolved request for practical quantum information applications. Researchers in China have proposed a N-photon state generation scheme that is feasible and scalable using lithium niobate on insulator circuits. The scheme was based on the integration of a common building block photon-number doubling unit (PDU) for deterministic single-photon parametric downconversion and upconversion. The PDU relies on a 107-optical-quality-factor resonator and mW-level on-chip power, which is within the current fabrication and experimental limits. N-photon state generation schemes, with cluster and Greenberger–Horne–Zeilinger state as examples, are shown for different quantum tasks… read more. […]