Metasurface interferometry toward quantum sensors

TLDR

Optical metasurfaces enable precise wavefront control of light, opening new avenues for integrated quantum technology. The study aims to entangle and disentangle two‑photon spin states at a dielectric metasurface. This is achieved by demonstrating a hybrid integrated quantum photonic system. Interfering single‑photon pairs at the metasurface produced a path‑entangled two‑photon NOON state with circular polarization, achieving a quantum HOM interference visibility of 86 ± 4 % and a fringe visibility of 86.8 ± 1.1 % in coincidence counts, thereby demonstrating high‑visibility metasurface‑induced path entanglement and promising high‑dimensional functionalities for imaging, sensing, and computing.

Abstract

Optical metasurfaces open new avenues for precise wavefront control of light for integrated quantum technology. Here, we demonstrate a hybrid integrated quantum photonic system that is capable to entangle and disentangle two-photon spin states at a dielectric metasurface. By interfering single-photon pairs at a nanostructured dielectric metasurface, a path-entangled two-photon NOON state with circular polarization is generated that exhibits a quantum HOM interference visibility of 86 $\pm$ 4%. Furthermore, we demonstrate nonclassicality and phase sensitivity in a metasurface-based interferometer with a fringe visibility of 86.8 $\pm$ 1.1 % in the coincidence counts. This high visibility proves the metasurface-induced path entanglement inside the interferometer. Our findings provide a promising way to hybrid-integrated quantum technology with high-dimensional functionalities in various applications like imaging, sensing, and computing.