Just five months after Schurig and colleagues published their theory that cloaking could be possible, researchers from the United States and England, supported by the Intelligence Community Postdoctoral Research Fellowship Program and the United Kingdom Engineering and Physical Sciences Research Council, have developed a cloak that can prevent microwaves from detecting objects. In their first successful experiment, they were able to cloak a copper cylinder.

"We have built an artificial mirage that can hide something from would-be observers in any direction," said cloak designer David Schurig, a research associate in Duke University's electrical and computer engineering department.

Cloaking uses special metamaterials which are mixtures of metal and circuit board materials such as ceramic, Teflon or fiber composite (see photo above) which deflects radar or light or microwaves so they flow around a 'hidden' object inside with little distortion, making it appear almost as if nothing were there at all. It differs from stealth technology, which does not make an aircraft invisible but reduces the cross-section available to radar, making it hard to track.

Viewers can see things because objects scatter the light that strikes them, reflecting some of it back to the eye. The cloak reduces both an object's reflection and its shadow, either of which would enable its detection.

For a start, the researchers developed a cloak to prevent microwaves from detecting objects. Like light and radar waves, microwaves usually bounce off objects, making them visible to instruments and creating a shadow that can be detected.

The result of the work which was done very quickly is not optimal and researchers say there is scope of improvement. The first working cloak was in only two dimensions and did cast a small shadow. The next step is to go for three dimensions and to eliminate any shadow.

An improved version could hide people and objects from visible light. In an ideal situation, the cloak and the item it is hiding would be invisible. An observer would see whatever is beyond them, with no evidence the cloaked item exists.

In a very speculative application, one could imagine 'cloaking' acoustic waves, so as to shield a region from vibration or seismic activity.