London, Sept 20 (ANI): After coming closer to creating an invisibility cloak, a research team, which includes an Indian origin researcher, is working on developing hidden portals - like the entrance to the railway platform that Harry Potter uses to get to Hogwarts.
A research team led by Xudong Luo at Shanghai Jiao Tong University has found out a way of developing hidden portals that look like a blank wall but contains invisible openings.
Physicist John Pendry of Imperial College in London's theoretical work along with an Indian scientist S. Anantha Ramakrishna, on metamaterials formed the basis of the new trick.
Metamaterials are structures pieced together from tiny electrical devices that allow them to interact with light in ways that are impossible for ordinary substances.
A metamaterial invisibility shield bends light smoothly around an object at its centre, like water flowing around a rock in a river.
The Shangai group is working on creating an object that, because of its unusual interactions with light, looks bigger than it really is.
A pillar made of such stuff, placed in the middle of an opening in a wall, could appear to fill the gap completely, whereas in fact there are open spaces to each side.
In 2003, Pendry and Ramakrishna showed that a cylinder of metamaterial could act as a magnifying lens for an object inside it.
"When you look at a milk bottle, you don't see the glass", Nature quoted Pendry, as saying.
Because of the way in which the milk scatters light, "the milk seems to go right to the edge of the bottle."
Luo and colleagues have shown that an even more remarkable effect is possible: the milk can appear to be outside the bottle.
"It's like a three-dimensional projector. I call it a super-milk bottle," said Pendry.
Lou's team opted for a more prosaic 'superscatterer'. They showed that such an object could be made from a metal core surrounded by a metamaterial with a negative refractive index.
The researchers focused their study on the way light interacts with a rectangular superscatterer placed in the middle of a wide opening in a wall, and find that, for the right choice of sizes and metamaterial properties, the light bounces back just as it does if there was no opening.
If someone passes through the concealed opening, they found, it becomes momentarily visible before disappearing again once they are on the other side.
However, the calculations so far only show concealment for microwave radiation, not visible light.
Pendry said that the problem in using visible-light metamaterials is that they tend to absorb some light rather than scattering it all into the magnified image, making it hard to project the image a significant distance beyond the object's surface.
Openings hidden from the naked eye aren't likely "until we get on top of these materials", he added. (ANI)
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