LONDON - Invisible gateways, like the one in Harry Potter, are a step closer to reality, thanks to a new theory developed by scientists.

With the help of a technique known as transformation optics, the research team from Hong Kong University and Fudan University in Shanghai has found a way to alter the pathway of light waves that could eventually allow them to develop portals that are invisible to the human eye, reports The Telegraph.

Pushing the laws of refraction and reflection to the limit, the researchers 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 efforts 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 advance 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: “People standing outside the gateway would see something like a mirror”.

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

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. It is an optical illusion,” he said.

The theory has been described in the New Journal of Physics. (ANI)