Walk up to any Harry Potter fan and ask which magical object featured in the series he or she would most want in real life and quite a few will put a Cloak of Invisibility high on the list. It’s the best tool one could need for any sneaking around Hogwarts or to make a run out to Hogsmeade.
But wishing for an invisibility cloak is just a fantastical pipe dream, right? You might as well ask for the Elder Wand while you’re at it. Not so fast, though: Turns out that a team of researchers at the University of Texas are about to take a crucial step in turning that fantasy into scientific reality.
A group of technical wizards from UT has proposed a design for a cloaking device that utilizes an external source of energy. The team of engineers believes this would allow a cloak to operate across a greater range of frequencies than have those depicted in previous blueprints.
A group of technical wizards from UT has proposed a design for a cloaking device that utilizes an external source of energy.
The nuts and bolts of such a device are described in the team’s paper, “Broadening the Cloaking Bandwidth with Non-Foster Metasurfaces,” which was published earlier this month in Physical Review Letters. The paper was co-authored by Andrea Alù, associate professor at the Cockrell School of Engineering, researcher Pai-Yen Chen and postdoctoral research fellow Christos Argyropoulos.
While experimenting with cloaking devices is nothing new, Alù and his team’s design is different from other models; previously proposed forms use passive technology, which means that they are not designed to draw energy from an external source. Other proposed designs are meant to use advanced artificial materials or other surfaces that suppress the scattering of light that bounces off of an object.
The battery-powered cloak is meant to overcome what the UT researchers believes are a few shortcomings innate with passive technology cloaks. Alù says, “Many cloaking designs are good at suppressing the visibility under certain conditions, but they are inherently limited to work for specific colors of light or specific frequencies of operation.”
In the paper, Alù and his team state, “we prove that cloaks can become broadband, pushing this technology far beyond current limits of passive cloaks. I believe that our design helps us understand the fundamental challenges of suppressing the scattering of various objects at multiple wavelengths and shows a realistic path to overcome them.”
The team has further proposed that such invisibility cloaks can be used to improve biomedical sensing, near-field imaging and energy harvesting devices.
Of course, don’t expect to find a fully functional invisibility cloak delivered by FedEx any time soon. Proposed cloak designs start off scattering radio waves, but the active, battery-powered model could help leapfrog the technology to make human eye detection more difficult.
And don’t feel bad if some of the scientific concepts behind an invisibility cloak don’t make a lot of sense to you. Just think of it in regards to Arthur C. Clarke’s Third Law:“Any sufficiently advanced technology is indistinguishable from magic.”