An ultrathin metasurface produces a network of entangled quantum photons

Artist’s impression of the metasurface converting incoming photons from a laser beam into quantum entangled photon pairs — © Igal Brener / Sandia National Laboratories

Scientists from Sandia National Laboratories and the Max Planck Institute have managed to produce an entangled photon array using a much simpler setup than those used so far.

Use metasurfaces to perform complex tasks with minimal equipment

L’quantum entanglement implies that two particles become so inextricably linked that the measurement or modification of one of them instantly affects its partner, regardless of the distance between them. This phenomenon is the basis of emerging technologies such as quantum computing and encryption.

Typically performed using large arrays of lasers, special crystals and other optical equipment, the generation of clusters of photons entangled can be tricky. This is why the authors of the new study, published in the journal Scienceturned to a much simpler device: a metasurface.

Presenting all kinds of exciting properties, these two-dimensional devices act like lenses by precisely manipulating the light passing through them. To do this, however, they do not use their curvature or their thickness, but nanometric structures, allowing researchers to perform a wide range of complex tasks (trapping atoms, producing holograms, etc.) with minimal equipment.

The new metasurface illuminated by a green laser — © Craig Fritz / Sandia National Laboratories

Taking the form of an ultra-thin sheet of glass, the metasurface used by the team was coated with nanostructures of gallium arsenide, a semiconductor material. When the metasurface is hit by a laser, some of the photons exiting the other side do so in entangled pairs, forming a veritable network.

A multi-tangle made in one step

Usually, performing a multi-tangle that requires more than two or three pairs turns out to be complicated “, details Igal Brener, principal researcher of the study. ” Nonlinear metasurfaces essentially allow this task to be accomplished in a single step where previously this would have required incredibly complex optical setups.. »

Being able to induce quantum entanglement in groups of photons at a time could have a wide range of applications for quantum computers, encryption, communication, and optics. But before that, the team says there’s still work to be done to maximize the effectiveness of the metasurface.

This new breakthrough comes just weeks after the announcement ofa record quantum entanglementhaving involved 14 photons.

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