Philip Ball reports in Nature:
Andrea Alù and Nader Engheta of the University of Pennsylvania in Philadelphia say that a ‘plasmonic cover’ could render objects “nearly invisible to an observer”. Their idea remains just a proposal at this stage, but it doesn’t obviously violate any laws of physics.
“The concept is an interesting one, with several important potential applications,” says John Pendry, a physicist at Imperial College in London, UK. “It could find uses in stealth technology and camouflage.”
…The key to the concept is to reduce light scattering. We see objects because light bounces off them; if this scattering of light could be prevented (and if the objects didn’t absorb any light) they would become invisible. Alù and Engheta’s plasmonic screen suppresses scattering by resonating in tune with the illuminating light.