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Optical Computer Made From Frozen Light
neutron_p writes "Scientists at Harvard University have shown how ultra-cold atoms can be used to freeze and control light to form the "core" - or central processing unit - of an optical computer. Optical computers would transport information ten times faster than traditional electronic devices, smashing the intrinsic speed limit of silicon technology. This new research could be a major breakthrough in the quest to create super-fast computers that use light instead of electrons to process information. Professor Lene Hau is one of the world's foremost authorities on "slow light". Her research group became famous for slowing down light, which normally travels at 186,000 miles per second, to less than the speed of a bicycle."
Where do I get one of these? No, I want it now
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Most of the positive fanatics write lots of papers; those who think it's not going anywhere (like me) don't. There are sound physical reasons to be skeptical, in my mind:
1) Wavelengths are too big: 1 micron is now a large number, and optics doesn't work much smaller than this.
2) There are no good nonlinearities. Anyone can make a linear OR gate optically, but to function as an effective digital technology you need nonlinearity and level restoration. This is missing in pure optical systems, except at very high power levels. The high power levels imply low density. There are some optical gates which process data in "femtoseconds," but ask them how long it takes to get to the next gate. Maybe someday someone will invent a great, low power, fast, optically nonlinear material. Don't invest in it yet.
3) The serious workers are now mostly working in combined electronic/optical modes. The speeds here are limited by the gate speeds of the electronics, just like normal computers. You have to then ask if optics is a good (cost effective, space efficient, low power...) replacement for wire. Ultimately, the answer is probably yes, but there's an awful lot of work to do before that's true (for the distances of a few centimeters in high density computers, that is).
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BTW, for those interested, here's a direct link to the "Light at Bicycle Speed ... and Slower Yet!" presentation - I was travelling about that speed in
my coldest car during a Colorado snowstorm.
e=mc^2 except where c is like slower and fuck, headache.
Imagine trying to harness today's 3GHz CPUs with 1930s lab bench equipment. Digital electronics could have seemed another universe, out of reach in a universe of alternate physics "beyond radio". If photonic computation is within reach at artifically lowered speeds, we might be just about to cross the watershed, like going from transistor to ENIAC.
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Her research group became famous for slowing down light, which normally travels at 186,000 miles per second, to less than the speed of a bicycle."
Ah, so she worked on IE.
became famous for slowing down light, which normally travels at 186,000 miles per second, to less than the speed of a bicycle.
ah yes, the Speed of a Bicycle (SoaB) metric for slow light.
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The best thing about frozen light is that you can put it in your freezer, so that when there's a blackout, it will thaw and then you'll have light.
And this means absolutely nothing to the non-supercomputer world. Light doesn't slow itself down for free. Freezing light for this proccess likely takes the expenditure equal to the GDP of a small country. At best, in the next 50 years there will be 2 frozen light optiocal supercomputers
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We need a conversion factor to BSUs (Bull Shit Units) for all of these standards.
In God we trust, all others require data.
Now all we need is Advanced Military Algoritms and Pre-Sentient Algorithms until we achieve Fusion Power and our units become twice as strong as our enemy's units.
Intellectual Integrity and Cyberethics may pose a problem however.
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and I thought we could safely rule out 'A' because it wasn't one of the given options? ;-)
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Metric BSUs or standard BSUs?
Obviously it's not simply a temperature thing, since most of space is absolute zero, and I can see stars and suns and stuff. So it's not freezing light as in freezing water.
So how exactly do you stop photons from moving? How does this affect relativity (e=mc^2)? How does this affect our perception of the universe - ie; if the light from the star that we think is 10,000 light years away is only moving 20mph or so, it could really be millions of light years away?
Does like, time slow down? My heads spinning. Freeze sounds like the wrong word.
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The speed of light is _only_ 186,000 mi/sec when traveling through a vacuum. Light travels at slower speeds through all other mediums (i.e. earth's atmosphere, glass, a super-cooled diamond, etc)
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From Wikipedia: 'In a sense, any light travelling through a medium other than a vacuum travels below c as a result of refraction. However, certain materials have an exceptionally high refractive index: in particular, the optical density of a Bose-Einstein condensate can be very high. In 1999, a team of scientists led by Lene Hau were able to slow the speed of a light beam to about 17 metres per second, and, in 2001, they were able to momentarily stop a beam.' Slowing light down is nothing new, it happens every time light travels through a medium other than the vacuum of space. Atmosphere, glass window, diamond, etc. It just so happens that we can now create in a laboratory these BEC's, a so-called "superfluid" which is basically a substance cooled to the point where nearly every atom collapses to the lowest quantum state (like, close to absolute zero). This gives it some interesting properties, like zero viscosity and an extremely high optical density. Hope that helps.
The title of this post clearly reads:
Science: Optical Computer Made From Frozen Light
We don't even have a diagram for a logic gate (or at least none are presented in the article) just some supposition in the article that such a thing could be used as a component. As for the 10x faster, where the hell did this number come from? Even if Moore's Law is slowing down (don't nit pick about it be about the number of components on a chip) it will make this "smashing" 10x advantage moot. Perhaps they refer to the speed of light in free space as opposed to signal speed copper. But even this doesn't make sense because signal speed in copper is about c/3.
What really maters is how fast a gate can be made to switch, how easy it is to fabricate enough of them to do something useful, and how close you can pack them together. Until someone can put down on paper the diagram of how this thing would work it is pointless to posit that it would be 10x faster.
Usually for these Pie-in-the-Sky type hype offerings it is common to claim 100x or 1000x or 1,000,000x times.
That BSEs might be used someday as parts in a Quantum computer would be a completely different thing, and those calculations that could be done quantumly would be trillions of times faster, but only for very specific algorithms. This article is not talking about that possibility, but classical computing and I think they have a lot of work to do just to demonstrate a single working component. Let alone claim BSE computers are here or just around the corner.
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Einstein showed there is no o bjective measure of speed. Of course, if a bicycle were to travel at the speed of light, it would be very heavy and very long, but, if you were the one riding it, you wouldn't notice...
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I'm going to have to disagree with other repliers on this one. In much of physics (such as relativity and particle physics) it is stated that nothing can travel faster than c, and that light *always* travels at c (never faster or slower). Then in optics you're told that the speed of light depends on the material the light is travelling in. Confusion is understandable.
If you want a picture of what's really going on, think of it this way: *photons* (the fundamental particles of light) always travel at the speed of light, c, as measured by any observer (like relativity says!). However, in optics, when we talk about "light" we don't usually mean individual photons, we mean a massive collection of them, and thus things change a bit. In vacuum, a light beam will travel at exactly c since all the photons travel at c. In a material, however, the photons are continually scattered by the atoms that make it up. These countless scattering events (which are essentially absorption and re-emission events) interfere and generate the final light-beam that we macroscopically observe. The interaction between the photons and the electron clouds in the material lead to time lags, if you will... so that the net macroscopic velocity appears reduced (even though, in principle, the photons travelling from one atom to the next were going at c).
There are experiments where light is "slowed" or "stopped" or even moved backward... and some where light even travels "faster than light." But what is travelling at these speeds is the emergent phenomenon (the envelope of the photon interference pattern), not the individual photons that make it up. Thus, even if the envelope of a photon wave pattern is travelling faster than c (i.e.: the calculated group velocity is >c), you still can't send a signal faster than c. The "no energy/signal can go faster than speed of light" rule is very much maintained. For more information on this, google the difference between "phase velocity" and "group velocity" of light, which will give you some insights.
The problem is that when introductory physics is taught, the difference between these different velocities is not mentioned (phase velocity != group velocity != photon velocity) And of course, news articles never mention it!!
I was going to mod, but I guess a reply is better.
regarding point (3)-- "ess temperature = less energy (e). the speed of light (c) decreases at the same rate as the square root of e." I call shenanigans. c is a constant here to relate the conversion of mass to energy (and vice versa). E does NOT reference heat energy.
If it did, the speed of light would increase for hot objects (and on hot days). Time effects would be experienced by stars and nuclear reactors.
1) Wavelengths are too big: 1 micron is now a large number, and optics doesn't work much smaller than this.
This poster is correct. Since I have a Ph.D. in the field and the parent obviously knows something about optics, I might as well respond to the parent's critics.
IR photons are BIG. Forcing light to bend around corners is difficult. A waveguide must have a very high index of refraction if it is to be used to bend light within a reasonable radius. To the extent a Bose-Einstein Condensate helps this problem is encouraging if you don't mind cooling your computer to 2 millikelvin.
The speed of these optical computers always seems to come down to limitations of the silicon processors that work in conjunction with the light.
It's just a Bose-Einstein Condensate. These projects take time. While we are enamored with this BEC project, some poor grad student is working on carbon doping. Higher doping might improve the world of electronics far more than another optical computer claim.
I visited Hau's website and did, though, enjoy her papers. I just don't think the press release accurately portrays the low engineering potential of this work.
Kudos to whoever is giving out low mod points to people whose jokes completely blow. I have seen "Funny,5" way too many times for observations that are just too painfully unfunny to read.
>In Soviet Russia, light freezes you!!
God, please stop.
Wait, if this is just refraction, then the light isn't slowed at all, right?
No, it is. Mentioning refraction is a little odd, as refraction is caused by the slowing of light, not the cause of the slowing of light.
Once you're out of free space, the speed that an electric field can move can be hugely affected by density, etc.
Think of it this way: in a high optical density material, light is so slow because it has to drag electrons around as it moves. Light's an electromagnetic field, after all, and electrons have an electric field.
Now, you could *also* consider on a very, very small scale (sub-sub-atomic) that the photons are in fact still traveling at the speed of light - it's just that they're interacting so often with the electrons present that their net speed is very, very, very low.