Engineers demonstrate metamaterials that can solve equations

Yesterday we had news of a reprogramable molecular computer.

Today, we go back to the future and get an analog computer made of microwave waveguides!

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.

phys.org, March 21, 2019 - Engineers demonstrate metamaterials that can solve equations.

This is going to take some 'splaining.

The first computer was thought up by Charles Babbage. Known as the "difference engine" it was a mechanical device that would do the maths required for correct astronomical tables. A set of wheels worked together as you stepped through each calculation. The step up from the calculator like difference engine would be the "analytic engine" which would be more powerful. Ada, the Countess of Lovelace, realized that you can get different results depending upon the series of steps taken and thus became the world's first computer programmer! The programming language, Ada, is named after her.

Wikipedia

Due to the precise mechanical work, Babbage did not live to see his engines built. Time would pass, and instead of steam and gears, vacuum tubes and electricity would be harnessed to create a digital computer. Then transistors came along and replaced tubes. Computer shrank in size as etching technologies developed along Moore's Law until we all have a computer on our phones allowing us to view movie clips of cats playing pianos!

"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."

In the article they try and explain what is happening and what is meant by imagining a music hall. If all the different ways sound could bounce off the various structures, you could then electronically reproduce the hall in a digital computer. Which is exactly what my Lexicon LX-15 does! (I know it is old, but so am I).

Doing the same thing as sampling the hall, they worked backwards and carved channels into the plastic to perform a "Fredholm integral equations of the second kind" which is some smarty pants math that does something like sum up linear equations over a blah, blah, blah.

Which they call "Swiss cheese" when finished (he, he, they cut the cheese!). You fire any microwave source at it, and out pops your answer! The system is called a "kernel" and each one would have to be specifically cut to solve some equation. But here is the real kicker...

"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."

How cool would that be? They said this should work with read/write CD/DEV ROM technology (when scaled down). You would be able to cut out repetitive programs on your own computer for... I don't know! It is so interesting and nerdy!

By thinking back to where it started, we might end up with nanocomputers that work on light waveguides like Sir Charles Babbage dreamed about from the start!

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.

a reply to: Phage


Neat!

I remember getting to play with one of the first HP calculators which was about 1/4 the width of my keyboard!! It was the first portable calculator to come out.

As a bored teen on Thanksgiving holiday, I went with my dad to work where I counted out the parts, ordered everything, replaced missing resistors, etc., then he soldered together my first computer: Sinclair ZX-81 (Heathkit I believe).

I would probably end up doing something silly like programming in Space Invaders or Galaga on my picosecond metamaterial analog computer! Maybe a fractal screen saver.

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.

(same source as OP)

Just to give you an idea of size.

As artificial intelligence algorithms are used more and more frequently, you could possibly off load some of the repetitive parts to a special purpose "Swiss chees" kernel. Maybe, some day, allow the program to write what it needs changed (or thinks needs changed), and we edge closer a true intelligence.

This all seems to be part of the "race to the bottom" as technology shrinks.

Or combine it with the "levitation by light" story, and you get a free floating, glowing brain! Probably chasing you down with lasers shooting from its third eye shrieking, "Exterminate!"

a reply to: TEOTWAWKIAIFF

So if understand this correctly, it's a plastic sponge in the form of a circuit or program? As in, the holes in the plastic material make up the program and they pass microwaves through it to execute the program?

If so that's pretty awesome. Though, i'm not sure if i'm missing something but how to they read the solution from it?

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.

Awesome!

When I was 11 or 12 I built a couple of disco balls for a birthday party, soldering together motors and parts from my younger brother's toys. Then built the round cases for it, cut plastic film in colors for the openings and played with resistance to slow it all down enough to look cool.

Kids need to lose their tablets and do some fun stuff like that. Or go out with a microscope, kill ants and observe them.

a reply to: dug88

Yes, that is how it works.

It doesn’t say how the encoded microwave message is read.

It is phased. If that makes a difference.

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.)

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.)

Hah, that's awesome. And, yes sorry OP.

And Phage, I actually had to search 'wooden coke bottle box' to see what this thing is and I was pleasantly surprised that such a thing existed at some point in time. Nice.

Edit to add:


Neat.

a reply to: Duderino

24 bottle variety.

As Ada could tell you, doing successive steps on data is how you achieve the results you want.

For example, sorting can be done in several different ways (measured in ‘big O’ notation usually in x^2, or log x, to determine efficiency). But almost all almost end up at the algorithm called “bubble sort” which is does what it’s name means, largest value is swapped forward (to the top, hence ‘bubble’). A rather simple comparison of values then either swap or stop.

So it would make sense to etch this algorithm into a kernel... even if it takes multiple ones because if you are using light (where this is headed), then even multiple layers would be crazy fast. Erm, lightning quick!

Anybody else have simple algorithms that would benefit from an optical waveguide analog computation meta material version?

Lol certainly quantum effects there
a reply to: Phage