Metalens-array–based high-dimensional and multiphoton quantum source

TLDR

Spontaneous down‑conversion in nonlinear crystals produces entangled photon pairs essential for quantum information and communications, yet conventional bulk setups are large and impractical for scalable applications. The study seeks to miniaturize the quantum source by integrating metalenses to replace bulky optical components. The authors combine a metalens array with a nonlinear crystal to achieve a substantially smaller down‑conversion device. The compact device is expected to enable miniaturized integrated quantum optical technologies. Published in Science, p.

Abstract

Metalens-array–based quantum source Spontaneous down-conversion is an exotic optical process in a nonlinear crystal in which a high-energy photon splits into two lower-energy photons that are quantum mechanically entangled. These entangled pairs are valuable commodities for quantum information processing and quantum communications. Because the experimental setup is usually performed with bulk optical components, there is a need to decrease the size scale for application. Li et al. combined an array of specialized metalenses with a nonlinear crystal and show that the scale of the process can be shrunk substantially. The approach should prove useful for developing miniaturized integrated quantum optical technologies. Science , this issue p. 1487