Harnessing high-dimensional entangled states of light presents a frontier for advancing quantum information technologies, from fundamental tests of quantum mechanics to enhanced computation and communication protocols. In this context, the spatial degree of freedom stands out as particularly suited for on-chip integration. But while traditional demonstrations produce and manipulate path-entangled states sequentially with discrete optical elements, continuously coupled nonlinear waveguide systems offer a promising alternative where photons can be generated and interfere along the entire propagation length, unveiling novel capabilities within a reduced footprint. Here we exploit this concept to implement a compact and reconfigurable source of path-entangled photon pairs based on parametric down-conversion in semiconductor nonlinear waveguide arrays. We use a double-pump configuration to engineer the output quantum state and implement various types of spatial correlations, exploiting a quantum interference effect between the biphoton state generated in each pumped waveguide. This demonstration, at room temperature and telecom wavelength, illustrates the potential of continuously coupled systems as a promising alternative to discrete multicomponent quantum circuits for leveraging the high-dimensional spatial degree of freedom of photons. Published by the American Physical Society 2024

中文翻译：

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非线性波导阵列中空间纠缠的可调谐生成


利用高维纠缠态的光为推进量子信息技术提供了前沿领域，从量子力学的基础测试到增强的计算和通信协议。在这种情况下，空间自由度特别适合片上集成。但是，虽然传统的演示使用离散光学元件按顺序产生和操纵路径纠缠态，但连续耦合非线性波导系统提供了一种很有前途的替代方案，可以在整个传播长度上产生光子并进行干扰，从而在更小的占地面积内揭示新的功能。在这里，我们利用这个概念在半导体非线性波导阵列中实现了一个基于参数下转换的紧凑且可重构的路径纠缠光子对源。我们使用双泵浦配置来设计输出量子态并实现各种类型的空间关联，利用每个泵浦波导中产生的双光子态之间的量子干涉效应。该演示在室温和电信波长下，展示了连续耦合系统作为离散多分量量子电路的有前途的替代方案的潜力，以利用光子的高维空间自由度。 美国物理学会 2024 年出版