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Scientists conjure true 'cloaking' device

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-Department of Physics
External Sites:
-Science Express
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For Immediate Release
Friday 26 May 2006

A way to vanish matter before your eyes has become a serious possibility thanks to theoretical research announced today by British and American scientists.

When built, the device theorised by the research could achieve a similar magical effect to that seen in Harry Potter movies, where the trainee wizard dons a special cape and becomes invisible.

The research suggests a way to build a 'cloaking' or shielding device that renders whatever is placed inside it invisible. It would also nullify the effects of other electromagnetic radiation - meaning that objects sitting within the cloak would be impervious to radar detection.

The scientists from Imperial College London and Duke University, USA, announced their findings in a paper published in Science Express today (26 May).

Professor Sir John Pendry discovers 'cloaking' device that could render whatever is placed inside it invisible

"Just as in the Harry Potter film, nobody would be able to see an object if it was cloaked, as it's in a spacewarp, and that's exactly what our stuff would do," says Professor Sir John Pendry Opens in new window of the Department of Physics at Imperial College London and first author of the research.

The researchers propose to build a special material that wraps around an object and which would 'grab' light heading towards it and make it flow smoothly around the object rather than strike it. To an observer the light would appear to have behaved as if there was nothing there.

Sir John explains the concept by likening it to water flowing around a stick in a stream. "Water flows around the obstacle and continues smoothly on behind the stick downstream. That's the idea behind our theory."

Study co-authors David Schurig and David Smith of Duke University, are now attempting to build the special material, called a metamaterial, that will do the grabbing of light and achieve this effect in reality. The first device is likely to be at a very small scale, just a few tenths of a centimetre across.

However, the special effects of the cloaking device would not be limited just to light rays, but would extend to all other field lines, including lines of force. This suggests other novel uses, for example in an interventional MRI scanner, where metallic instruments and other sensitive measuring equipment cannot be used due to the scanner's very strong magnetic fields. Instruments contained within such a cloaking device could however be used safely.

Unlike other stealth or cloaking solutions currently under development, the proposed device would also operate across a range of frequencies, not just one. "Ours would be a broadband cloak," says Sir John.

Since the cloak could also be tuned to apply to any ranges of frequency on the electromagnetic spectrum, it could also shield objects at the radio frequencies used by radar. In fact, says Sir John, this is where the device may eventually make the biggest impact.

Fortunately, he says, the technical challenge of making the device is less exacting than that for another of his ideas, the perfect lens, and he expects the first to be made within one or two years, for radar applications.

"If you can make the right metamaterials you will be almost there. They should be much easier to make than those required for perfect lenses, since our cloaking device doesn't need to be made to a perfect quality to achieve the right result."

The inspiration for the theory builds on work undertaken by Sir John and a former graduate student Andrew Ward over a decade ago, which demonstrated not only a theoretical new way of steering light but, as it was later realised, a means of 'ripping' a hole in space.

"What this device would really do is a bit like making a black hole" said Sir John,"There would be no communication between the object that is cloaked and the outside world."

The research was supported with funding from EPSRC (Engineering and Physical Sciences Research Council, UK) and DARPA (Defense Advanced Research Projects Agency, US).


For more information please contact:

Abigail Smith
Imperial College London Press Office
Tel: +44 (0)20 7594 6701
Mob: +44 (0)7803 886248

Notes to editors:

"Controlling Electromagnetic Fields" appears in Science Express on 26 May 2006.

Authors: J. B. Pendry1, D. Schurig2 and D. R. Smith2

1 Department of Physics, The Blackett Laboratory, Imperial College London, London SW7 2AZ, UK

2 Department of Electrical and Computer Engineering, Duke University, Box 90291, Durham, NC 27708, USA

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