A team led by scientists at Duke University's Pratt School of Engineering said Thursday they have demonstrated the first working "invisibility cloak." The cloak, introduced in May, deflects microwave beams so they flow around a hidden object inside with little distortion, making it appear as if nothing were there at all.

Cloaks that render objects essentially invisible to microwaves could have a variety of wireless communications or radar applications, according to the researchers.

The researchers manufactured the cloak using "metamaterials" precisely arranged in a series of concentric circles that confer specific electromagnetic properties. Metamaterials are artificial composites that can interact with electromagnetic waves in ways where natural materials cannot reproduce.

Earlier scientific approaches to achieving invisibility often relied on limiting the reflection of electromagnetic waves, the researchers said. Scientists often attempted to create cloaks with electromagnetic properties that, in effect, cancel those of the object meant to be hidden. In the latter case, a given cloak would be suitable for hiding only objects with very specific properties.

David Smith, professor of electrical and computer engineering at Duke, and others on the project produced the cloak with electromagnetic specifications determined by a new design theory proposed by Sir John Pendry of Imperial College London.

The team reported its findings in Science Express, the online publication of the journal Science. The research was funded by the Intelligence Community Postdoctoral Fellowship Program.

A video about the invisibility cloaking research can be downloaded here.