Scientists Claim Portals 'Invisible Doorways' Closer To Reality

telegraph.co.uk - Using a technique known as transformation optics, the researchers have revealed a way to alter the pathway of light waves that could eventually allow them to create portals that are invisible to the human eye.

Pushing the laws of refraction and reflection to the limit, the team from Hong Kong University and Fudan University in Shanghai, describe the concept of a “a gateway that can block electromagnetic waves but that allows the passage of other entities”.

The gateway uses transformation optics and a "superscatterer" made from photonic crystals to create an 'optical illusion', forcing light and other forms of electromagnetic radiation into complicated directions to hide the portal.

Previous attempts at an electromagnetic gateway were hindered by their narrow bandwidth, only capturing a small range of visible light or other forms of electromagnetic radiation.

The breakthrough, described in the New Journal of Physics, also has the added advantage of being able to be switched on and off remotely.

Dr Huanyang Chen, from the Physics Department at Hong Kong University of Science and Technology, said that " people standing outside the gateway would see something like a mirror".

However, despite being theoretically possible many practical issues have to be overcome, the team admitted.

Professor Ulf Leonhardt, Chair in Theoretical Physics at the University of St Andrews, said the technique was an extreme version of the affect you have when you watch fish in a glass tank.

He said the deflection of light as it moves from the air to the glass to the water makes the fish seem bigger and in a different part of the tank that in reality.

"By placing photonic crystals at the right angle they can reflect light making a hole invisible," he said. "It is an optical illusion."

One practical use for the breakthrough could eventually be cloaking devices for the military.