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The new research from IBM builds upon its discovery of light emitting nanotubes FETs, pictured here, which were developed in 2003.  (Source: J A Misewich, IBM)
IBM continues its march towards creating an optical computer with another breakthrough.

IBM is among several companies betting big on optical computing as the next big thing to replace traditional electricity based computing.  Optical computing is seen as a stepping stone for even more advanced computing technologies such as quantum computing.

In order to build a quantum computer, three key light-based components are needed:  transistors to form a CPU, I/O equipment, and memory/storage media.  IBM already has the I/O side well on the way, thanks to its advanced fiber optics research and switching breakthroughs.  It has also seen great gains in memory and storage media.  Finally, it could likely adapt its switching technology from the I/O research to form a transistor analog.

All the pieces are in place, though still in early stages, however; one critical component was missing -- something to make intense light pulses on a nanoscale.  IBM needed a nanolaser and that's exactly what its researchers have created.

The new nanolaser will likely be analogous to the clock in a full nanocomputer, producing the driving impulses.  Further nanolasers could convert electric signals from peripherals to laser impulses to be sent to the CPU.  The system could also be used more modestly in a shrunk version of fiber optic network on traditional electric systems.

The breakthrough device utilizes a familiar friend -- the carbon nanotube.  Carbon nanotubes, formed from interconnected hexagonal carbon rings, are also being studied as a material for traditional electric transistors, thanks to their great conduction, strength, and flexibility.

The new research, reported in the August 25 Nature Nanotechnology journal, uses a special nanotube-based field effect transistor to generate light impulses on a nanoscale.  The light impulses are then routed by a pair of tiny nanocavity mirrors.  By controlling the nanocavity mirrors, the wavelength of the optical emissions, the spectral and spatial distributions of the emitted light and the efficiency of the emissions could all be controlled.

An optical computer could theoretically perform computations at the speed of light (though only the speed of light in mediums such as glass, not the more commonly used speed of light in a vacuum).  This would allow for faster computers.  Also, the light impulses would likely generate less waste heat then electric circuits, which would allow for denser hardware.

A quantum computer could take these gains even farther, computing at faster than the speed of light, thanks to bizarre quantum effects such as entanglement.  However, a quantum computer would require manipulation of single electrons, where an optical computer only would require larger light-controlling components.

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RE: Speed of light
By Fnoob on 8/25/2008 5:58:15 PM , Rating: 2
I assumed, prolly incorrectly, that electromagnetic energy (electricity) travels at the speed of light. So if it doesn't due to resistance, how close is it? Is it slowed down by some fraction of 1%? So this new tech would increase the speed by that amount? I'm underwhelmed and likely missing something here.

RE: Speed of light
By Some1ne on 8/25/2008 6:09:07 PM , Rating: 4

Basically, it depends on what sort of link the electricity is propagating through. It seems reasonable to assume that a propagation of at least 80% the speed of light in a vacuum is easily attainable.

So if the article is referring to the propagation speed, having signals traveling at the speed of light is only good for a gain of <= 20%. Not bad, but not revolutionary either.

RE: Speed of light
By 9nails on 8/25/2008 11:31:01 PM , Rating: 5
Ok, so the advantages of speed in copper connects vs. light connections is arguable.

The important thing to take away is that when you ramp up the density of those copper connections they tend to bleed data between each other, generate heat, resistance creates power inefficiencies, they are susceptible to external electro-mechanical interference, and can be taken out by odd effect of nano-whiskers causing short circuits. Circuits designed in light, theoretically, have none of these problems. The benifits may seem minimal, but the importance of this breakthrough are significant. This breakthrough allows one to tightly pack in circuits preforming at high frequencies with less power loss and heat. From a simple perspective; cooler circuits, more bandwidth and cleaner signals equate to faster computers.

RE: Speed of light
By JonnyDough on 8/26/2008 2:34:20 AM , Rating: 2
In addition to that, some further reading for those who require a better understanding of photons and electrons. I was doing some of my own research about size differences. Turns out, there is no relative "size"!

RE: Speed of light
By AnnihilatorX on 8/27/2008 1:15:06 PM , Rating: 2
Well the propagation of signal base on electricity is equal to speed of light. Electron drift velocity within a conductor is only around millimetres per second. But that's irrelevant to speed which signal transmits.

An analogy of electrons drifting in a conductor is easily visualized as follows:
Imagine a tube containing a line of touching spheres without gaps. Pushing the ball one end will affects the one at the other end near speed of light due to electromagnetic interactions in microscopic level on sphere surfaces; though each sphere only travels at the speed you pushed them in.

Optical transmission is only better than copper not due to speed signal propagates, but solely due to 2 major advantages: The non-existence of leakage effects on a narrow channel and the much lower noise; especially when electronics are pushing to lower voltage levels at smaller manufacturing process to minimise heat dissipation.

You can see that resistance, hence heat dissipation, is only an indirect factor why optical is superior to copper.

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