Since the Harry Potter books and movies (at the latest), people have wanted to be invisible. Now, researchers from Duke University have unveiled a perfect invisibility cloak. The catch? The object was only a few centimeters large and the cloaking was done with microwaves, not visible light - so you will not yet be able to buy that invisibility cloak on Amazon.

The feat is still being hailed scientifically. This is not the first invisibility cloak created, but it is the closest that researchers have come to perfection. Invisibility cloaks work by bending electromagnetic waves around an object through the use of metamaterials, or materials not found in nature. Instead of seeing the object, a viewer sees behind it. But previous attempts have struggled with creating metamaterials that do not cause reflections around the corners. In addition, cloaking an object with an invisibility shield made the background look slightly darker, discolored, or just not quite right.

The researchers at Duke University fixed that problem by fashioning metamaterials in a diamond shape. That way, the rays would be reflected perfectly. When they used the cloak, they were able to hide a small cylinder - 7.5 centimeters wide and 1 centimeter tall - from an electromagnetic wave, with properties that should translate, in theory, to visible light.

So what's the problem? The cloak only works in one direction, unfortunately. "It's like the card people in Alice in Wonderland," Professor David Smith, one of the study authors, explained to BBC News. "If they turn on their sides you can't see them but they're obviously visible if you look from the other direction."

Regardless, the cloak is still a scientific breakthrough. Even if the cloak does not yet work with the visible spectrum, Popular Science points out that it has implications for future work in communications and defense technology. After all, the visible spectrum is not the only time in which invisibility could be useful.

The study was published in the latest issue of Nature Materials.

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