Synopsis: Fish Eye Lens Could Entangle Atoms

An optical design called Maxwell’s fish eye lens could produce quantum entanglement between atoms separated by an arbitrary distance, new calculations show.
Synopsis figure
J. Perczel et al., Phys. Rev. A (2018)

Maxwell’s fish eye lens—proposed more than 150 years ago—is an optical system that bends light along arcs that converge to a single point. New theoretical work investigates how a single photon would pass from one atom to another inside a fish eye lens system. The results show that the photon-mediated interaction between the atoms is independent of their separation distance, implying that a fish eye lens could entangle atoms more efficiently than similar cavity-based devices.

As originally conceived, the fish eye lens is a spherically symmetric material whose index of refraction decreases as one moves out from the center. This lens can focus all light rays emanating from an arbitrary point A to a corresponding point B located on the opposite side of the lens. Recently, researchers have been debating whether or not this focusing would be limited by diffraction—would a detector placed at B record a perfect image of a source emitting from A?

In their quantum approach to this debate, Janos Perczel, Peter Kómár, and Mikhail Lukin, from the Massachusetts Institute of Technology, Cambridge, and Harvard University, replace the source and detector with single atoms. They imagine the atoms in a 2D cavity version of the fish eye and calculate that a photon emitted by one atom will initially spread out and fill the entire area of the lens before concentrating at the position of the second atom. This concentration is diffraction limited, implying that the fish eye cannot produce perfect images. However, the second atom efficiently absorbs the photon, which translates into a strong interaction for entangling the atoms. The authors propose testing these predictions with photons confined to a thin, layered structure in which the refractive index varies like a fish eye lens.

This research is published in Physical Review A.

–Michael Schirber

Michael Schirber is a Corresponding Editor for Physics based in Lyon, France.


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