Entanglement generation using cryogenic integrated four-wave mixing

Cryogenic integrated nonlinear photonics can provide fundamental building blocks for scalable photonic quantum computing and optical interfacing among different platforms. Here, we investigate the spontaneous four-wave mixing effect in an integrated silicon waveguide with cryogenic operating conditions (4 K) and employ the system to generate the entangled photon-pair source, one of the key elements of photonic quantum information applications. We experimentally prove that even at cryogenic temperatures, the four-wave mixing effect in silicon waveguides is still an effective method to generate quantum photonic sources. The cryogenic photon-pair source is verified over multiple frequency channels within a bandwidth of similar to 2 THz. Furthermore, the source is used to generate high-quality frequency-multiplexed energy-time entangled states. Our results will advance the development of cryogenic nonlinear photonics and scalable integrated photonics for quantum information processing. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement