California – A study published in the Journal Science created a two-dimensional ultra-thin “invisibility cloak” that could give the illusion that a three dimensional object disappeared, something that brings to mind Harry Potter’s famous cloak.

The team of researchers from the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley, built the cloak in such a way it could fit the shape of the object perfectly, covering it up like it does not exist.

Despite being only 80 nanometers thing, which is a microscopic size, the principles behind the technology should enable it to be scaled-up to conceal macroscopic items.

Researchers have worked out how to make objects invisible with a material that is thin enough to be made into a cloak, like the one featured in the Harry Potter films. Credit: Warner Bros. Pictures / International Business Times

“This is the first time a 3D object of arbitrary shape has been cloaked from visible light,” study co-author Xiang Zhang, director of UCB’s Materials Sciences Division and a world authority on metamaterials, said in a press release. “Our ultra-thin cloak now looks like a coat. It is easy to design and implement, and is potentially scalable for hiding macroscopic objects.”

It also creates a “metasurface” that reflects light around it in a way that no one could notice there is an object beneath the cloak. The experiment was made by covering up around a three-dimensional object that was the size of a few biological cells.

“Creating a carpet cloak that works in the air was so difficult we had to embed it in a dielectric prism that introduced an additional phase in the reflected light, which made the cloak visible by phase-sensitive detection,” said co-lead author Xingjie Ni, a recent member of Zhang’s research group who is now an assistant professor at Penn State University, in a news release.

“Recent developments in metasurfaces, however, allow us to manipulate the phase of a propagating wave directly through the use of subwavelength-sized elements that locally tailor the electromagnetic response at the nanoscale, a response that is accompanied by dramatic light confinement.”

The 80 nanometre thick film is made from gold “nanoantennae” blocks that interfere with the normal scattering of light waves. Photograph: Xiang Zhang group/Berkeley Labor/PA

How was it possible?

The interaction of light with matter is what enables human eye to see. The rules that govern these interactions can be avoided when working with metamaterials, whose optical properties arise from their physical structure rather than their chemical composition.

After ten years, Zhang and his research team have came to find a way to curve the path of light or bend it backwards in metamaterials. This way it is possible to make objects optically undetectable.

When doing the experiment, after covering an approximately 1,300 square micron under the cloak, the light reflected off the surface of the skin cloak was identical to light reflected off a flat mirror, making the object invisible.

“A phase shift provided by each individual nanoantenna fully restores both the wavefront and the phase of the scattered light so that the object remains perfectly hidden,” says co-lead author Zi Jing Wong, also a member of Zhang’s research group.

Source: Science Magazine