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Researchers Create First All Optical Nanowire NAND Gate
mhore writes "Researchers at the University of Pennsylvania have created the first all optical, nanowire-based NAND gate, which paves the way towards photonic devices that manipulate light to perform computations. From the release: 'The research team began by precisely cutting a gap into a nanowire. They then pumped enough energy into the first nanowire segment that it began to emit laser light from its end and through the gap. Because the researchers started with a single nanowire, the two segment ends were perfectly matched, allowing the second segment to efficiently absorb and transmit the light down its length.' The gate works by shining light on the nanowire structure to turn on and off information transported through the wire. The research appeared this month in Nature Nanotechnology (abstract)."
I think we are wasting the potential of future optics if we think in binary, as this team is doing.
Optics scream for multilevel logic.
---- Booth was a patriot ----
Not sure where you read this... Per TFA:
[quote]
A NAND gate, which stands for “not and,” returns a “0” output when all its inputs are “1.”
[/quote]
And the Nature Nanotechnology article's summary says nothing specific.
That isn't exactly what he meant. Current computer science will be mostly obsolete, but not the concept of computer science. It will adapt, it has to.
---- Booth was a patriot ----
I remember reading over twenty years ago of an all-optical nand gate. This was pre-web, so it might not be easy to find, but I remember the article. The gate was much much larger, although the developers (of course) said that they expected to be able to shrink it in size to suitable dimensions. And a good part of the article was a prediction of an all optical computer within 5 years. The logic behind this prediction was that all steps in creating the state of technology that we had the were created very incrementally, We used hand labor to create the first ICs. We used those to create powerful computers. We created CAD software for those to develop even smaller computers. But all of those steps had been done and were in place, the prediction was that it should take no more than 5 years to substitute in optical technology for electronic technology into computer design software and start cranking out optical devices.
Not sure what happened to that optical nand gate from over two decades ago. Maybe it just couldn't shrink down. Maybe it was just falsified. Or maybe someone already has optical computers but will not share them with us conspiracy theorists. But I'm jaded now and not so inclined to get excited on yet another "first" announcement.
I'm an American. I love this country and the freedoms that we used to have.
It's not that humans are not adaptable, it's that parallel computing is hard for humans to figure out. Linear execution lends itself to all kinds of easy abstractions: loops, branches, methods, etc. Parallel computing, not so much. Mutexes are awful. The best we've got is message passing and functional programming, but even that is hard to design correctly to be both understandable and exploit inherent parallelism.
Y'know what's even harder to design? Analog computing. Holy cow. Remember, digital computing was invented by Touring before we even had built a computer. It's easy to visualize how it works. My brain explodes though trying to imagine a fuzzy-logic analog equivalent of a touring machine.
I used to think that AI research combined with neuroscience would figure out a simple solution to this problem, but it's increasingly seeming like, no, it's even complicated in the brain.
So people can pine for analog memristor computation, and analog optical computing all they want, but the hardware is the easy part here. Get the software side solved, and if you build it they will come. But it's not because we aren't used to these problems, it's because these problems are really really hard.
The two major disadvantages of all Optical processing in the past were:
1/ The Wavelength of light is much larger than the structures used in modern day chips. So the optical circuity wouldn't be as dense as modern day electronics.
2/ When you turn off an optical signal it gets turned into heat (i.e the transistor goes black) not true in electronics as there is no electrical flow when the transistor is off. This causes a theoretical optical devices run hotter than electronic ones and therefore hurting density yet again.
Optics and optical processing have there place (especially processing communications data) but for high density processing these two problematic are very problematic.
As per D'Morgan's Law, it's possible to build a computer using either NAND or NOR gates. But not w/ AND or OR gates, if inverters don't exist.