Invisible doorways have long been the stuff of fiction: Harry Potter, for example, entered a hidden portal to catch a train at King’s Cross station in London. Now, a team has disguised a gateway in the real world.
The trick is to use a metamaterial — an artificial structure whose components collectively exhibit properties that the individual components do not. Metamaterials can be used to bend light in unusual ways and, with the right design, they can become ‘superscatterers’ that look larger than they really are.
Huanyang Chen of Xiamen University in China, Rui-Xin Wu at Nanjing University, also in China, and their colleagues built a superscattering metamaterial from iron-rich ceramic rods arranged in parallel. They placed their metamaterial on one side of a 5-centimetre-wide gateway. When they shone microwave radiation at the opening, the metamaterial stopped the waves from moving through the gateway, rendering it ‘invisible’ at microwave wavelengths.
The team confirmed that changing patterns of electron density at the surface of the metamaterial are responsible for repelling the light.