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Scientists Freeze Pulse Of Light
Smitty825 writes "After slowing down light to slow speeds, scientists at Harvard University have been able to stop light for a very brief period of time without destroying its energy. The article explains how it is different from this previous light-stopping science story - this will hopefully help the development of quantum computers and ways to communicate over long distances without being eavesdropped on."
The article mentions clearly:
"We have succeeded in holding a light pulse still without taking all the energy away from it," said Mikhail D. Lukin, a Harvard physicist.
This is somehow different from "...without destroying its energy." like it is stated in the posting. Maybe a subtle detail, but not quite the same.
However, a briliant achievement. Kuddos.
BBC News has an article which speaks a bit more to Quantum crytography.
"Quantum cryptography might provide very secure forms of electronic encryption, because the process of eavesdropping on an electronic message would introduce errors in the message, garbling it."
"This would allow you to exchange a key on a public channel, but whereas any classical system can be broken by an eavesdropper, in quantum cryptography you would always find out if someone was looking at your message," Professor Zubairy told BBC News Online."
"Academicians are more likely to share each other's toothbrush than each other's nomenclature."
Cohen
Like I did here.
More detailed articles about the research can be found here or here.
Larkin's article itself is here.
Any physics nerds want to explain it to us?
Bob Shaw, Other Days, Other Eyes. A poster above mentioned it.
Just because you're paranoid doesn't mean there isn't an invisible demon about to eat your face
That may be how traditional optical communications works. Quantum crypto, otoh, relies on the light being put in a certain polarization state by the sender. It's designed so that a stream of single photons go from sender to receiver; there can be no equipment in-between. If an intermediary views this photon en-route, it disturbs the polarization seen by the receiver. Because of the way the sender and receiver can agree on which photons were correctly measured, any aberrations (intercepted photons) are discarded. The most you can hope for is a denial-of-service.
Here's a better explanation than I can muster.
"I assumed blithely that there were no elves out there in the darkness"
They're not stopping the photon. They're simply storing it in several atoms quantum spin. Then they hit it again with a laser and get the earlier pulse back out of the quantum spin stored in the atoms. It's rather limited because, quoting from Science News
However your post should be modded funny, because it's a witty, clever response rather than the usual worn jokes which somehow seem to get modded up all too frequently.
Reminds me of a childrens story I read once about a time machine, which was based on a nutty inventor who managed to build a car that got progressively faster. First of all it took a minute to get a specific distance, then 30 seconds, then 1 second, until in fact it took no time at all and then less than no time to get there until it ended up travelling backwards in time...
Conversion Rate Optimisation French / English consultant
You've got the right idea, but the Uncertainty Principle puts a lower bound on the mutual uncertainties in time and energy measured, ie,
4 * pi * uncertainty in time * uncertainty in energy >= Planck's constant
(I believe you can use the standard deviation as the uncertainty here.) This "law" that results from our model for quantum mechanics thus tends to put a limit on how fast a quantum/optical computer can be.
To-do List: Receive telemarketing call during a tornado warning. Check.
This article gives a few more details, and here is the actual press release.
no, that's false. the universal speed limitation is the speed of light in a vacuum. Because light passing through matter moves slower than it does through a vacuum, it's perfectly possible to move faster than the "local" speed of light. Physicists have studied this by firing high-speed particles into crystals. Basically the particle creates a shockwave, a sort of optical equivalent of a sonic boom. It's called Cherenkov radiation if you want to look it up.
The author of this post asserts his moral rights.
Some people have posted claims that this is similar to the earlier experiments of Lene Hau, where the light pulse was indeed stored as excitations in trapped atoms (either in a BEC as in Hau's case, or in a vapor cell as in Lukin's earlier experiment).
This is quite different from what's going on here. In this experiment, two lasers are used to polarize the atomic vapor as a function of position, and then bouncing light off that polarization gradient. Think of what happens when you put light in between two highly reflecting mirrors, and let it bounce back and forth. Then think about what happens if you nest thousands of these mirrors within each other, so that if the photon leaks out of one, it has to deal with the next one, only one wavelength away. Since the photon is spending so much time bouncing back and forth, it doesn't really have a chance to escape the gas, and so we say that it's trapped.
It's essentially a new way of making a high quality cavity.
The Light of Other Days is by Steven Baxter and Arthur C. Clark.
The only reason we have the rights we have is that people just like us died to gain those rights. -- Cheerio Boy
Sorry friend, but he is correct and you are wrong.
He stated the 'color' of our photo receptors. Although our photo receptors pick up C, Y, and M -- it is because their colors (as he said) are R, G, and B.
ie: the Red Photoreceptor reflects RED, that is why it is a red colored photoreceptor. Since it reflects RED, it picks up BLUE and GREEN, which make one of the (secondary) colors you mentioned.
You are also wrong saying that RGB is used for pigment. Pigment gets its color by absorbing color, and you see what is reflected. RGB is used for TVs and Monitors where there is a direct source of light.
Cheers!