基于周期极化铌酸锂波导的高维路径纠缠态

High-dimensional path entangled states based on periodically poled lithium niobate waveguides

摘要:

路径纠缠态是利用空间路径进行信息编码的量子资源，它在量子测量、量子通信等领域具有十分重要的应用价值。本文基于周期极化铌酸锂（periodically poled lithium niobate，PPLN）波导提出一种产生双光子高维路径纠缠态的理论方案。利用耦合模式方程，分析了光在波导系统中电场横向分布模式，推导出参量下转换过程产生的双光子态函数。通过激发特定的相位匹配条件，调控泵浦光的振幅和相位，从波导系统中将产生确定性双光子路径纠缠态。该方案可从两波导系统推广至多波导系统，从而产生高维路径纠缠态。方案无需对波导极化区域长度进行精确控制，具有较强的稳定性和扩展性。这对推动高维路径纠缠源的发展起到重要作用，并为集成化量子信息处理提供了新的可能性。

Abstract:

Path entangled states are vital quantum resources which use spatial modes to encode information. They have important applications in quantum measurement, quantum communication and so on. In this article, we proposed a scheme for generating high-dimensional path entangled states based on periodically poled lithium niobate (PPLN) waveguides. The transverse electric field distribution modes of light in the waveguides are analyzed by using the coupled mode equations, and the biphoton states generated from the spontaneous parametric down-conversion process are derived. The deterministic path entangled states can be generated from the waveguides by exciting specific phase matching conditions and tuning the amplitudes and phases of pump beams. This scheme can be extended from two-waveguide system to multi-waveguide system to generate high-dimensional path entangled states. It does not need to precisely control the length of PPLN, and has strong stability and scalability. It paves the way for the development of high-dimensional path entanglement sources, and also provides new possibilities for integrated quantum information processing.