U of T engineers create electromagnetic invisibility cloak

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If Harry Potter's invisibility cloak was created like those in labs today, the young wizard may have been visible at least if one looked at visibility over all wavelengths.

Scientists and engineers have been trying to pull the 'invisibility cloak' out of fantasy and into reality lately, and they've been making some impressive progress. Now, a team of University of Toronto engineers have gone past using strange new 'metamaterials' to make a cloaking field using electromagnetic waves.

"We've demonstrated a different way of doing it," George Eleftheriades, a professor of electromagnetics at U of T, said in a statement. "It's very simple: instead of surrounding what you're trying to cloak with a thick metamaterial shell, we surround it with one layer of tiny antennas, and this layer radiates back a field that cancels the reflections from the object."

This version of cloaking is apparently very adaptable to larger scales simply by using more antennas, and although the antennas used in the test would be bulky in practice, according to Eleftheriades, they could produce printed, flat antennas in the future that could become like a blanket or skin over the object.

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This version of cloaking is so far effective against radio waves, so it can be used to shield an object against being detected by radar. However, the antennas are tunable. It won't yet work with visible light, and there's quite the wavelength difference to make up there, but as the technology develops, that might not be too far behind. That could produce a true invisibility cloak, but in a way that's more Star Trek than Harry Potter.

Electromagnetic cloaking has military applications, of course, but this one could be very useful for improving cellphone reception, by cloaking buildings and other obstacles, to prevent them from interfering with signals.

The paper that Prof. Eleftheriades and his PhD student Michael Selvanayagam published, titled Experimental demonstration of active electromagnetic cloaking appears in the journal Physical Review X as of today.

(Image courtesy: University of Toronto)

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