Toward practical quantum optics: Multiphoton qubits from LNOI

https://phys.org/news/2023-02-quantum-optics-multiphoton-qubits-lnoi.html

"generate N-photon state deterministically; photon number doubling happens with 100% efficiency, keeping spectrum unchanged, with unlimited numbers of photons... using lithium-niobate-on-insulator (LNOI) platform providing ultrastrong χ(2) nonlinear interaction... PDU is universal for generation of N-qubit states, for examples, on-chip designs for N-photon Fock state, cluster state, and GHZ state... DPDC with 107 Q-factor microring, within current limits of fabrication and experimentation"