&Bullet; physics 14, p84

When modulated by laser beams, a surface of polarizable meta-atoms can entangle the properties of a photon in a variety of controllable ways.

WJM Kort-Kamp et al. [1]

Precisely designed 2D surfaces, so-called metasurfaces, comprise nanoscale arrays of antenna-like structures that scatter light in a way that is not known in nature. Metasurfaces have recently been adapted to the quantum domain, with atomic-scale designs that can manipulate individual photons. Wilton Kort-Kamp and colleagues from Los Alamos National Laboratory, New Mexico, are now adding a new dimension to these quantum meta-surfaces and propose a compact photonic platform that continuously changes its light scattering properties in space and time. The “space-time-quantum meta-surface” enables real-time control over coherent light-matter interactions and could enable high-dimensional information coding and high-capacity communication systems.

Quantum meta-surfaces consist of “meta-atom” building blocks – nanoscopic features whose optical properties result from their composition and their geometric design. These meta-atoms are typically arranged in a single layer to create a platform that provides spatial control over quantum light. Rotating some meta-atoms relative to each other can, for example, establish correlations between the spin of a photon and its path through the meta-surface. Kort-Kamp and his colleagues added a temporal component to a meta-surface by modulating the optical properties of the meta-atoms through interference between two pump laser beams. When a single probe photon crosses the meta-surface, color, path, rotation, and spin can all be entangled, depending on how much electrical polarization each meta-atom experiences when it is illuminated by the pump lasers.

The researchers say their space-time quantum meta-surfaces open a new avenue for research at the interface of flat optics, quantum information, and nanophotonics. The concept could lead to new functionalities, such as reconfigurable entanglement for quantum communication, actively controlled single-photon quantum emitters or spatially and temporally tunable quantum materials for sensor and imaging applications.

–Rachel Berkowitz

Rachel Berkowitz is Corresponding Editor for physics based in Vancouver, Canada.


  1. WJM Kort-Kamp et al., “Spacetime quantum meta-surfaces”, Phys. Rev. Lett.127, 043603 (2021).

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