AP-S Turnstile

Professor Pendry\´s (Imperial College, London) observation [1] from 2006 is an example of the excitement in the electromagnetic research community about the potential of metamaterials to create the equivalent of Harry Potter\´s invisibility cloak. Back then, a research group at Duke University demonstrated how a two-dimensional structure, composed of 10 fiberglass rings covered with sub-wavelength arrays of copper elements, could help "channel" an incident EM wave in the microwave frequency range around a copper cylinder, minimizing a scattered signal. Earlier this year, a group at UC Berkeley raised the stakes by fabricating the "cloak" using nanotechnology (for the sub-wavelength elements), so that the target could be made to "disappear" at wavelengths approaching the visible spectrum. Exciting as these metamaterial-based developments have been, they remain far from real-life applications. A recent report in The Economist discusses what is achievable in practice using the current hide-and-seek military technology. This column presents some highlights from the report