Cooperative optical wavefront engineering with atomic arrays

TL;DR

This paper demonstrates how ultrathin atomic arrays can be engineered to manipulate light at the nanoscale, enabling applications like focusing, steering, and converting light's angular momentum through collective electric and magnetic responses.

Contribution

It introduces a method to use atomic arrays as quantum nanophotonic Huygens' surfaces for full phase control of transmitted light, combining electric and magnetic collective excitations.

Findings

Atomic arrays can focus light to subwavelength spots.

They can steer light at different angles for optical sorting.

They can convert between different angular momentum states.

Abstract

Natural materials typically interact weakly with the magnetic component of light which greatly limits their applications. This has led to the development of artificial metamaterials and metasurfaces. However, natural atoms, where only electric dipole transitions are relevant at optical frequencies, can cooperatively respond to light to form collective excitations with strong magnetic, as well as electric, interactions, together with corresponding electric and magnetic mirror reflection properties. By combining the electric and magnetic collective degrees of freedom we show that ultrathin planar arrays of atoms can be utilized as atomic lenses to focus light to subwavelength spots at the diffraction limit, to steer light at different angles allowing for optical sorting, and as converters between different angular momentum states. The method is based on coherently superposing induced electric and magnetic dipoles to engineer a quantum nanophotonic Huygens' surface of atoms, giving full $2\pi$ phase control over the transmission, with close to zero reflection.