We demonstrate a bright, narrowband, compact, quasi-phase-matched single-crystal source generating path-polarization-entangled photon pairs at 810 nm and 1550 nm at a maximum rate of 3 x 10~(6) s~(-1) THz~(-1) mW~(-1) after coupling to single-mode fiber, and with two-photon interference visibility above 90percent. While the source can already be used to implement quantum communication protocols such as quantum key distribution, this work is also instrumental for narrowband applications such as entanglement transfer from photonic to atomic qubits, or entanglement of photons from independent sources.
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机译：我们展示了一个明亮，窄带，紧凑，准相位匹配的单晶源，它在810 nm和1550 nm处产生路径偏振纠缠的光子对，最大速率为3 x 10〜（6）s〜（-1）耦合到单模光纤后的THz〜（-1）mW〜（-1），双光子干涉能见度超过90％。尽管该源已经可以用于实现量子通信协议（例如量子密钥分发），但这项工作还有助于窄带应用，例如从光子到原子量子位的纠缠转移，或来自独立源的光子的纠缠。
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