Polarization-entangled photon pairs from lithium niobate metasurfaces.

IF 3.1 2区物理与天体物理 Q2 OPTICS

Optics letters Pub Date : 2025-04-01 DOI:10.1364/OL.559126

Quanrui Mo, Chaoxin Shi, Xinding Zhang, Jianjun Zhang, Jihua Zhang

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引用次数: 0

Abstract

Flat optics has emerged as a promising platform for ultrathin polarization-entangled sources via spontaneous parametric downconversion in subwavelength-thick nonlinear films or metasurfaces. However, previous schemes typically required multiplexing two films or two meta-structures with different orientations. Here, we propose a nonlinear metasurface composed of a single silica grating atop a lithium niobate film to generate polarization-entangled photon pairs. By engineering the angular dispersion of metasurface resonances, adjusting the pump frequency, and leveraging the polarization correlated transverse phase matching, the |HH〉 and |VV〉 states are simultaneously enhanced by over 2000 times, while the |HV〉 and |VH〉 states remain similar when compared to the pure film. Therefore, the degree of polarization entanglement is significantly improved. Furthermore, by tuning the pump polarization and film orientation, and applying spatial filtering, the concurrence of the two-photon state is optimized to near one, meaning maximal entanglement. Such an ultrathin and spatial-separated-entangled photon-pair source will be useful in realizing miniaturized quantum photonic systems for various applications.

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铌酸锂超表面的偏振纠缠光子对。

平面光学已成为通过亚波长厚非线性薄膜或元表面的自发参量下变频实现超薄偏振纠缠源的一个前景广阔的平台。然而，以前的方案通常需要复用两个不同方向的薄膜或两个元结构。在这里，我们提出了一种由铌酸锂薄膜上的单个二氧化硅光栅组成的非线性元表面，用于产生偏振纠缠光子对。通过设计元表面共振的角色散、调整泵浦频率以及利用偏振相关的横向相位匹配，"HH "和 "VV "态同时增强了2000多倍，而 "HV "和 "VH "态则与纯薄膜保持相似。因此，偏振纠缠的程度显著提高。此外，通过调整泵浦偏振和薄膜方向，并应用空间滤波，双光子态的并发度被优化到接近于 1，这意味着最大纠缠度。这种超薄、空间分离的纠缠光子对源将有助于实现微型量子光子系统的各种应用。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Optics letters 物理-光学

CiteScore

6.60

自引率

8.30%

发文量

2275

审稿时长

1.7 months

期刊介绍： The Optical Society (OSA) publishes high-quality, peer-reviewed articles in its portfolio of journals, which serve the full breadth of the optics and photonics community. Optics Letters offers rapid dissemination of new results in all areas of optics with short, original, peer-reviewed communications. Optics Letters covers the latest research in optical science, including optical measurements, optical components and devices, atmospheric optics, biomedical optics, Fourier optics, integrated optics, optical processing, optoelectronics, lasers, nonlinear optics, optical storage and holography, optical coherence, polarization, quantum electronics, ultrafast optical phenomena, photonic crystals, and fiber optics. Criteria used in determining acceptability of contributions include newsworthiness to a substantial part of the optics community and the effect of rapid publication on the research of others. This journal, published twice each month, is where readers look for the latest discoveries in optics.