[论文解读] Polarization-entangled photon pair generation from an epsilon-near-zero metasurface

Wenhe Jia, Grégoire Saerens+6 more|arXiv (Cornell University)|May 6, 2024

Metamaterials and Metasurfaces Applications被引用 5

一句话总结

该论文展示了一种纳尺度的偏振纠缠光子对源，利用耦合到近零介电常数材料的等离子体超表面的偏振纠缠光子对，能够在无需额外组件的情况下直接生成Bell态。

ABSTRACT

Polarization-entangled photon pair sources are essential for diverse quantum technologies, such as quantum communication, computation, and imaging. However, the generation of complex polarization-entangled quantum states has long been constrained by the available nonlinear susceptibility tensor of natural nonlinear crystals, necessitating a cumbersome and intricate setup for additional coherent superposition or post-selection. In this study, we introduce and experimentally demonstrate a nanoscale polarization-entangled photon pair source utilizing an artificially-engineered metamaterial platform. This platform is based on a plasmonic metasurface that is strongly coupled to an epsilon-near-zero (ENZ) material. By precisely engineering resonances at both pump and signal/idler wavelengths, and leveraging the field enhancement provided by the ENZ effect, the photon pair generation efficiency of the 68-nm-thick metasurface is significantly boosted. More notably, the ENZ metasurface platform facilitates versatile manipulation of the system's anisotropic second-order nonlinear susceptibility tensor, enabling direct control over the polarization states of the photon pairs, which leads to the generation of a polarization-entangled Bell state without the need for additional components. Our approach opens a new avenue for the simultaneous photon pair generation and quantum state engineering in a compact platform.

研究动机与目标

• 为量子技术提供紧凑、集成的偏振纠缠光子源的需求提供动机。
• 提出一种将等离子体超表面与近零介电材料相结合以增强非线性产生的超材料平台。
• 在实验上展示ENZ超表面使直接生成偏振纠缠光子对成为可能，无需事后选择或额外光学元件。

提出的方法

• 设计一个与ENZ材料强耦合的等离子体超表面，以在泵浦和信号/闲模波长处增强场强。
• 在泵浦和信号/闲模波长处调谐共振以通过非线性过程提升光子对产生。
• 利用二阶非各向同性的非线性张量来操控偏振态并产生纠缠。
• 直接从超表面产生偏振纠缠Bell态且无需辅助组件的演示。

实验结果

研究问题

• RQ1 ENZ辅助的超表面是否能在没有事后选择或额外光学元件的情况下直接生成偏振纠缠光子对？
• RQ2 如何通过工程化的各向异性二阶非线性张量实现对Bell态生成的控制？
• RQ3 超表面厚度和谐振调谐对光子对产生效率有何影响？

主要发现

• 68 nm厚的超表面实现偏振纠缠光子对的产生。
• ENZ超表面能够直接控制偏振态以在没有额外组件的情况下生成Bell态。
• 在泵浦和信号/闲模波长处的共振被设计用来通过场增强来提升非线性产生。
• 该平台在紧凑型外形中实现了光子对产生与量子态工程的同时展示。