Going quantum with metamaterials Metasurfaces should allow wafer-thin surfaces to replace bulk optical components. Two reports now demonstrate that metasurfaces can be extended into the quantum optical regime. Wang et al. determined the quantum state of multiple photons by simply passing them through a dielectric metasurface, scattering them into single-photon detectors. Stav et al. used a dielectric metasurface to generate entanglement between spin and orbital angular momentum of single photons. The results should aid the development of integrated quantum optic circuits operating on a nanophotonic platform. Science, this issue p. 1104, p. 1101 Metasurfaces are demonstrated to operate in the quantum optical regime. Metasurfaces based on resonant nanophotonic structures have enabled innovative types of flat-optics devices that often outperform the capabilities of bulk components, yet these advances remain largely unexplored for quantum applications. We show that nonclassical multiphoton interferences can be achieved at the subwavelength scale in all-dielectric metasurfaces. We simultaneously image multiple projections of quantum states with a single metasurface, enabling a robust reconstruction of amplitude, phase, coherence, and entanglement of multiphoton polarization-encoded states. One- and two-photon states are reconstructed through nonlocal photon correlation measurements with polarization-insensitive click detectors positioned after the metasurface, and the scalability to higher photon numbers is established theoretically. Our work illustrates the feasibility of ultrathin quantum metadevices for the manipulation and measurement of multiphoton quantum states, with applications in free-space quantum imaging and communications.

中文翻译：

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用于多光子干涉和状态重建的量子超表面

使用超材料实现量子化 超表面应该允许超薄表面取代体光学元件。现在有两份报告表明超表面可以扩展到量子光学领域。王等人。通过简单地将多个光子穿过介电超表面，将它们散射到单光子探测器中来确定多个光子的量子态。斯塔夫等人。使用介电超表面在单光子的自旋和轨道角动量之间产生纠缠。结果应该有助于开发在纳米光子平台上运行的集成量子光学电路。科学，这个问题 p。1104 页。1101 超表面被证明在量子光学范围内工作。基于共振纳米光子结构的超表面使创新类型的平面光学器件成为可能，这些器件的性能通常优于大块组件的能力，但这些进步在量子应用方面仍然未被探索。我们表明，可以在全介电超表面中在亚波长尺度上实现非经典多光子干涉。我们同时使用单个超表面对量子态的多个投影进行成像，从而能够对多光子偏振编码状态的幅度、相位、相干性和纠缠进行稳健的重建。一光子和二光子状态通过非局部光子相关测量重建，偏振不敏感点击检测器位于超表面之后，理论上建立了更高光子数的可扩展性。