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Light Stopped, Held And Re-emitted By A Crystal
nherc writes: "An article in Nature talks about an incredible new crystal that can actual stop and hold light to be later emitted. It's mentioned light has previously been "slowed" by super cooled gases, but this certainly blows that away. They mention this could be a major step towards quantum computing."
optical ram that is a crystal matrix that actually holds the image and energy?
comment directly in my journal
The article in Scientific American super cooled gases refers to super cooled gases, not crystals. Like the article says, doing this in a room tempature solid makes it much more feasible for use in solid state computing.
Could this be used to create more efficient solar panels? The photons are converted directly into energy, "stored" in the atoms. Rather than re-release the photons as light, would it be possible to capture that energy and convert it into something more useful?
My understanding of optics is rather lacking... something is nagging at the back of my mind telling me that this wouldn't work...
-- Minds are like parachutes... they work best when open.
I was going to post this as well, AFAIK it was a short story in which the main character went to somebody who manifactured these.
These 'slow glasses' were put close to beautiful spots and left there to soak up the imagery, then you could buy them and put them in your living room and see what they saw for a few years (wouldn't it be way cool to have a huge 'picture window' of a waterfall that freezes in winter etc.)
IIRC the story ended with the character noticing that the artisan had some glasses of his family when his wife was still alive.
Does anybody remember the title/author of this story?
-- the cake is a lie
A lot of people have been saying that light only goes at c in a vacuum. This isn't quite right.
Light goes always at c, period. When it goes through a solid, a better metaphor is that it has to slalom around the atoms in the solid. Of course due to QM it's really more like that Charles Addams cartoon with a ski track leading up to a tree, splitting around, and continuing on. At this point, classical approximations stop making sense, and you have to start talking about amplitudes. You can get the Feynman New Zealand videotapes here. It's an excellent but basic and easily understandable introduction to quantum electrodynamics.
In any event, this doesn't seem to be the same mechanism (unless the amplitudes get stuck as if the photon were going in a loop). It appears to be a similar mechanism, as pointed out elsewhere, to glow-in-the-dark paint. Terribly exciting, but not foundation-shattering, unfortunately. It would be a lot of fun if it were.
Another minor wrinkle is that c is very slightly faster than the speed of light in a vacuum, because a vacuum isn't quite empty. Particles come into the vacuum and immediately annihilated each other all the time. You can theoretically get rid of these by putting a vacuum between two plates so close together that these virtual particles can't form.
If we can stop the emission of light and trap the little photons, then what is to say we can't determine their spin, hence have a good look at everyones wonderful quantum encrypted messages. Stuff a crystal of this in the fiber and start to monitor the structure of the data packets, pick out your favourite light encrypted message, pass on, then look at the trail it made.
I'm old, my brain is addled, but being able to stop light, or its immediate emission, has to have counter intelligence uses.
Were this experiment conducted in conjunction with one measuring the quantum entaglement of those particles in the medium used to "store" the light, I wonder what effect it would have on the spin of the particles on the other end?
A little simpler: a) Quantum entangle the Rb particles (or some of them) with those at a distance. Observe spin.
b) perform this experiment (the one used to "store" light).
c) Observe the spin of the remote particles.
Any change? This would further explain the effects of Quantum Entanglement because not only would the spin of those particles not included in the experiment theoretically change, but one would know it wasn't a change caused by observation alone.
"You are not a beautiful and unique snowflake."...Tyler Durden
How long can they keep the light stopped without too much degradation of the signal?
When his defense asked, "Which computer has Jon Johansen trespassed upon?" the answer was: "His own."
I actually don't see how this can be applied to quantum computing, yet.
:)
This sounds almost exactly like an optical transistor, except that a transistor actually is an amplifier.
To make it more like a transistor, imagine a 2 part crystal; part A is continually primed to be discharged, laser like. Part B is the light capturing component. A 'gate' laser turns B on and off, an input laser is the signal, and the lazed output is the output.
Quantum computing and quantum mechanics deals with superposition and tunneling, to my understanding, so unless they can feed in 4 inputs, freeze the crystal, and then get one 'correct' output when they unfreeze it, I fail to see how this is quantum.
Given that I described a transistor, I can see this as being critical to an optical computer
Source = input
Gate = freezing laser
Drain = output
You can make an optical and gate this way:
Combine input A and B into one beam. If they are in phase (both true) their output signal amplitude doubles. If they are out of phase (one true, one false) their output amplitude is zero. Pass this combined signal through two crystals.
Pass a *second* 'clock' signal as well that happens to be out of phase and half the amplitude of a true signal. The first crystal fires true when the clock and input signal cancel to produce a '1'. The second crystal fires false when the clock and the input signal combine to produce a '-1'
GPL Deconstructed
if the crystals store the light then you store all the light that would have been reflected (including hopefully radar gun waves) then you can release the light later when you're in you garage... hmm would that mean you would see a movie of all that stored up light, or would it get all masshed together...if not then could these crystals be used for video cameras?
Hmm.. this is interesting...
Some of you may remember that uncrackable quantum encryption can be created by using a pair of photons. The problem is that the transmitter and receiver would have to be line of sight, or possibly over fiber. I wonder if two of these crystals can be used to trap the photons individually for later analysis.. Don't know if the process of entrapment within the crystal will destroy the quantum effect that makes this sort of crptography possible, IANAQP....
-fc
. echo -e \\04 >
I'm nowhere near qualified to ponder this, but...
If they could store light in a medium, in this case the yttrium silicate crystal, then one other property of light being that it is infinitely compressable, does that mean that we can use that same crystal as a battery that we could charge an infinite amount of energy into? Think laptop battary with the life of 1 year. (Or if the crystal becomes unstable at one point because of the amount of energy in it, make a bomb that releses pure energy and leaves no trace of itself?)
Sometimes I wish I was a plumber, then I'd know how to deal with other people's shit.
If they've actually stopped the light, then the velocity is 0, therefore wouldn't the uncertainy in position be infinite (delta p)*(delta x) > (h-bar), so if that were true, how would you get the light to come back out the same crystal?
I'm not a physicist or anything I just have a high school physics backgrounds, and I'm just wondering.
"Knowledge makes us accountable." - Che Guevara