Metasurface interferometry toward quantum sensors

Philip Georgi,Christine Silberhorn,Marcello Massaro,Harald Herrmann,Thomas Zentgraf,Basudeb Sain,Kai-Hong Luo,Nicola Montaut,Thomas Weiss,Guixin Li

doi:10.1038/s41377-019-0182-6

Abstract

Optical metasurfaces open new avenues for the precise wavefront control of light for integrated quantum technology. Here, we demonstrate a hybrid integrated quantum photonic system that is capable of entangling and disentangling two-photon spin states at a dielectric metasurface. Via the interference of single-photon pairs at a nanostructured dielectric metasurface, a path-entangled two-photon NOON state with circular polarization that exhibits a quantum HOM interference visibility of 86 ± 4% is generated. Furthermore, we demonstrate nonclassicality andphase sensitivity in a metasurface-based interferometer with a fringe visibility of 86.8 ± 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 develop hybrid-integrated quantum technology operating in the high-dimensional mode space in various applications, such as imaging, sensing, and computing.

Highlights

Integrated quantum technology is widely used to enable quantum applications in various systems for secure quantum communication[1,2,3] as well as in quantum simulation[4,5,6,7] and quantum metrology[8]
To quantify the quality of the quantum interference and the entanglement that takes place at the metasurface, we compare the visibility of the HOM dip obtained for the metasurface with a reference experiment
The reference experiment is inspired by Grice and Walmsley[33] and allows us to determine an upper bound on the achievable HOM visibility, which is approximately 89 ± 5%

Summary

Introduction

Integrated quantum technology is widely used to enable quantum applications in various systems for secure quantum communication[1,2,3] as well as in quantum simulation[4,5,6,7] and quantum metrology[8]. Our metasurface allows the generation of path-entangled NOON states with circular polarization due to the quantum interference effect. Passing the same metasurface the second time, the generated path-entangled two-photon spin state can be disentangled without introducing additional phase information.

Results

Conclusion