Rodríguez Echarri Álvaro, Cox Joel D, García de Abajo F Javier
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08 860 Castelldefels, Barcelona, Spain.
Center for Nano Optics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
Nanophotonics. 2022 Jan 21;11(5):1021-1032. doi: 10.1515/nanoph-2021-0736. eCollection 2022 Feb.
Entangled photons are pivotal elements in emerging quantum information technologies. While several schemes are available for the production of entangled photons, they typically require the assistance of cumbersome optical elements to couple them to other components involved in logic operations. Here, we introduce a scheme by which entangled photon pairs are directly generated as guided mode states in optical waveguides. The scheme relies on the intrinsic nonlinearity of the waveguide material, circumventing the use of bulky optical components and their associated phase-matching constraints. Specifically, we consider an optical waveguide under normal illumination, so that photon down-conversion can take place to excite waveguide states with opposite momentum in a spectral region populated by only two accessible modes. By additionally configuring the external illumination to interfere different incident directions, we can produce maximally entangled photon-pair states, directly generated as waveguide modes with conversion efficiencies that are competitive with respect to existing macroscopic schemes. These results should find application in the design of more efficient and compact quantum optics devices.
纠缠光子是新兴量子信息技术中的关键元素。虽然有几种方案可用于产生纠缠光子，但它们通常需要笨重的光学元件来将其耦合到逻辑操作中涉及的其他组件。在此，我们介绍一种方案，通过该方案，纠缠光子对直接作为光波导中的导模状态产生。该方案依赖于波导材料的固有非线性，避免了使用庞大的光学元件及其相关的相位匹配约束。具体而言，我们考虑在正常照明下的光波导，以便可以发生光子下转换，从而在仅由两个可及模式填充的光谱区域中激发具有相反动量的波导状态。通过额外配置外部照明以干涉不同的入射方向，我们可以产生最大纠缠的光子对状态，直接作为波导模式产生，其转换效率与现有的宏观方案相比具有竞争力。这些结果应在更高效、紧凑的量子光学器件设计中得到应用。
