First demonstration of a working invisibility cloak

Although the new cloak demonstrates the feasibility of the researchers' design, the findings nevertheless represent a "baby step" on the road to actual applications for invisibility, said team member Steven Cummer, a professor of electrical and computer engineering at Duke.

The researchers said they plan to work toward developing a three-dimensional cloak and further perfecting the cloaking effect.

Although the same principles applied to the new microwave cloak might ultimately lead to the production of cloaks that confer invisibility within the visible frequency range, that eventuality remains uncertain, the researchers said.

"It's not yet clear that you're going to get the invisibility that everyone thinks about with Harry Potter's cloak or the Star Trek cloaking device," Smith said.

To make an object literally vanish before a person's eyes, a cloak would have to simultaneously interact with all of the wavelengths, or colors, that make up light, he said. That technology would require much more intricate and tiny metamaterial structures, which scientists have yet to devise.

Collaborators on the study included Jack Mock and Bryan Justice of Duke; John Pendry of Imperial College London; and Anthony Starr of SensorMetrix in San Diego, Calif. Pendry's research is supported by the United Kingdom's Engineering and Physical Sciences Research Council.