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For Nader Engheta of the University of Pennsylvania's School of Engineering and Applied Science, one of the loftier goals in this field has been to design metamaterials that can solve equations. This "photonic calculus" would work by encoding parameters into the properties of an incoming electromagnetic wave and sending it through a metamaterial device; once inside, the device's unique structure would manipulate the wave in such a way that it would exit encoded with the solution to a pre-set integral equation for that arbitrary input.
This approach has its roots in analog computing. The first analog computers solved mathematical problems using physical elements, such as slide-rules and sets of gears, that were manipulated in precise ways to arrive at a solution. In the mid-20th century, electronic analog computers replaced the mechanical ones, with series of resistors, capacitors, inductors and amplifiers replacing their predecessors' clockworks.
As the field of metamaterials developed, Engheta and his team devised a way of bringing the concepts behind analog computing into the 21st century. Publishing a theoretical outline for "photonic calculus" in Science in 2014, they showed how a carefully designed metamaterial could perform mathematical operations on the profile of a wave passing thought it, such as finding its first or second derivative.
Now, Engheta and his team have performed physical experiments validating this theory and expanding it to solve equations.
"Our device contains a block of dielectric material that has a very specific distribution of air holes," Engheta says. "Our team likes to call it 'Swiss cheese.'"
The Swiss cheese material is a kind of polystyrene plastic; its intricate shape is carved by a CNC milling machine.
"Controlling the interactions of electromagnetic waves with this Swiss cheese metastructure is the key to solving the equation," Estakhri says. "Once the system is properly assembled, what you get out of the system is the solution to an integral equation."
"This structure," Edwards adds, "was calculated through a computational process known as 'inverse design,' which can be used to find shapes that no human would think of trying."
"Even at this proof-of-concept stage, our device is extremely fast compared to electronics," Engheta says. "With microwaves, our analysis has shown that a solution can be obtained in hundreds of nanoseconds, and once we take it to optics, the speed would be in picoseconds."
The researchers conducted their experiment with microwaves; as such, their device was roughly two square feet, or about eight wavelengths wide and four wavelengths long.
Scaling down the concept to the scale where it could operate on light waves and be placed on a microchip would not only make them more practical for computing, it would open the doors to other technologies that would enable them to be more like the multipurpose digital computers that first made analog computing obsolete decades ago.
originally posted by: Phage
a reply to: TEOTWAWKIAIFF
I built an analog computer (more of a calculator) from a kit when I was 11 or 12. It used nichrome wires as variable resistors. Electric sliderule, pretty much.
originally posted by: Phage
a reply to: Duderino
I made a psychedelic light box thingy out of a wooden coke bottle box. A string of blinking Christmas lights, one in each bottle section, and a frosted piece of plexiglass to cover it.
The blinking was completely random of course, but damn if it didn't make cool patterns and match the music. Quantum stuff, I'm sure.
Tried to make a strobe light with an old record player motor. That didn't work out very well.
(Sorry T, but you've gotta admit your OP is pretty esoteric.)