# Metasurface interferometry towards quantum sensors

## TL;DR

This paper demonstrates a dielectric metasurface that can generate and manipulate entangled two-photon states, enabling high-visibility quantum interference and phase sensitivity for advanced quantum sensing applications.

## Contribution

It introduces a hybrid integrated quantum photonic system using dielectric metasurfaces to generate and control entangled photon states with high interference visibility.

## Key findings

- Achieved 86% HOM interference visibility with metasurface-generated entangled photons.
- Demonstrated nonclassicality and phase sensitivity in a metasurface-based interferometer.
- Showcased potential for high-dimensional quantum functionalities in sensing and imaging.

## 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.

---
Source: https://tomesphere.com/paper/1908.04988