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Single Photons Bounced Off Orbiting Satellite
KentuckyFC writes "If we're ever going to benefit from the perfect security of quantum communication, we're going to need ways of transmitting entangled photons around the globe and certainly further than the current record of 144km through the atmosphere. Anton Zeilinger at the University of Vienna and colleagues have taken an important step towards this by bouncing individual photons off the Ajisai geodetic satellite (essentially a space-based disco ball) which is orbiting at 1400km. The group says the experiment is an important proof of principle for satellite-based quantum communications."
Not to mention photons are like words: you shouldn't use those you don't understand. Is it a wave or is it matter? Huh, Mr. Smarty Pants? Oh, what's that you say? A boson followed by a long explanation, how utterly predictable! Ha, you would say that. No. I want answers and I wanted them back when the church would persecute you for publishing them!
We need something smaller. Go back to the lab, anything larger than a Planck Length is unacceptable. And only 1400km? So help me god, if you can't express the distance it travels in double up arrow notation or tetration, I don't want to hear about it. Come on people, this is real science, not some religious mumbo jumbo (6,000 years? Is that the absolute limit of your imagination!?)
My work here is dung.
There's no place like localhost
This is just an elaborate game of pong, isn't it...
I record my sleeptalking
My work here is dung.
... does quantum communications (not quantum computers) actually serve any potentially useful purpose? Or is it just another way for researchers to get a nice fat grant and a for a load of network equipment companies a decade down the line flog yet more replacement network equipment at a juicy markup? This isn't a troll , I'm just a bit suspicious about all the hype surrouding QC when so far we've yet to see a single usable example of anything from this research anywhere in the world.
Also if anyone spins me the line about it being unbreakable I'll take it with a large pinch of salt. I have nothing to base my cynicism on other than time and time again supposedly secure and unbreakable systems have been broken and I don't see why QC should be any different. Harder yes , but different? Hmm...
did they have it go through two slits when it came back down?
There's a bunch of sattelites floating around up there that anyone could just bounce lasers off of?
Why hasn't this been used to bring high speed wireless access to people in remote locations? Is it just too hard to aim? Is the target moving constantly?
Ah, from some angles, this experiment proves the opposite. You need the photons to be "entangled". That means effectively in their own little world, not intereacting with the universe in any way. Shooting them up through 10^38 atoms of the atmosphere and bouncing them off a satellite is the exact opposite of entanglement.
Call me Old School, but when I was a kid, we had this thing called Heisenberg Uncertainty. Obviously, with the advent of Dark Matter, Quantum Entanglement and a Beowulf Cluster of XBox 360's, we don't need to worry about that.
Humor your old man... tell me how we got around that?
Scientists later found that the photon had been Photoshopped.
It must have been something you assimilated. . . .
Real security improvements. There is no proof that there is not a trivial way to factorise multiples of large prime numbers, which is the basis of most current encryption standards. There are alternatives, but again there is no proof that these cannot be cracked quickly.
;-)
Even though it is unlikely that someone will have a mathematical breakthrough that would allow your PDA to break 2kb keys, we know that a lot (maybe all) of these algorithms could be cracked with a quantum computer. It is possible that the US NSA already has such a computer, maybe together with Russia, China and Bill Gates
Quantum encryption is proven to be uncrackable without showing that someone is listening. With a preamble of two-way communications you can have a connection that is proven to be absolutely secure, and no breakthrough in mathematics or technology will break it.
If the photon has to get from point A to point B, then what is the advantage to quantum communications? Is it because the photon can be sent _before_ the data, which will then be sent by entanglement? Can someone explain it so my dumb mechanical engineering ass will understand it? I'm sure I'm not the only one who'd love to hear it. Thanks.
It is dangerous to be right when the government is wrong.
People are still puzzling over how the world's largest rave got started. It seems that once a light show started from what appeared to be a giant disco ball in space people everywhere got out their glow sticks, drugs and pacifiers and started dancing.
You are using English. Please learn the difference between loose and lose; they're, there, and their; your and you're.
We got a decent firing photon cannon.
Absolute power corrupts absolutely. indymedia
How can they possibly align the mirror so that a single photon bounces back to the detector? Surely a single-atom imperfection would be enough to deflect it across the room, and a few atoms would deflect it to the next country
I am expecting some quantum genius to tell me that it doesn't matter if it misses the detector because one from a parallel universe will hit it anyway!
Fuck. This site is unreadable at this point. This is the first time I've been back in two months. I was hoping that it might have been fixed by now.
I never expected Slashdot to succumb to javascript. I am very disappointed. I suppose I could try Lynx and see if it can retrieve a readable page from slashdot, but I don't expect so.
I'll check back in another two months to see if Slashdot has recovered from this devastating design decision. (I see the lower numbers of comments on the stories now indicate that I am not the only one who feels this way)
Put photons in a box together with some dim lightning until they are entangled
Then remove one photon and shoot it towards the sattelite
Then wait for the box to wobble when the first photon hits
Now you can be POSITIVE that it is your own backscatter! Go on, DoD, start DROOLING!
And yet again the moderators on here prove that anyone who dares to question the prevailing "wisdom" on /. gets marked as a troll.
The Heisenberg Uncertainty Principle is not a physical "law" rather it is a summation of other observations and it has been "short-cutted"
Imagine, you May have a quantum entangled pair in a box. How do you know if the box is full? If you shine anything in you will disturb the pair. So you send a single photon through a beam spliter. One path is clear the other goes through the box. The beams then recombine to create an interference pattern. Since you slit the single photon, it has a 50/50 shot of sending the photon through the box.
Now, if the box and it is empty then the beam(s) will create an interference pattern regardless of the path. If the box is full and the photon goes through the box then no light will be detected (and the entagled pair ruined). BUT if it goes down the open path and there is something in the box then there will be no interference pattern.
You have just shown that position of an object in the box without effecting it. You have just violated the HUP.
Now in the above design you have a 50/50 shot of sending the photon through the box. But as it turns out, so long as there is a "chance" that it COULD go through the box, the experiemnt still works. Therefore you can add additional beam splitters between the box and the 1st splitter, directing one side into the open path, increaing the success rate to and arbitrarily high level.
Oh great...
I can't wait until someone at the RIAA figures out how to protect music with quantum DRM. You get to listen to a song ONCE, then it doesn't exist anymore.
They will charge PER listening.
- For the complete works of Shakespeare: cat
People have been bouncing single photon's off of the Moon for almost 40 years, using Lunar Laser Ranging, or LLR.
Typically, with LLR a dense "pancake" of photons (maybe 1 meter across and a few mm deep) is shot at the LLR site on the Moon, and one photon returns per shot.
Ajisai is a relatively large Japanese satellite intended for Satellite Laser Ranging (SLR). Even though the SLR return is typically many photons, not just one, the ratio of (photons received back / photons sent) is still extremely tiny, and I rather doubt that they are sending one photon up to get one back.
So, this sounds more like a press release than an actual advance.
Most Expensive Disco Ball...Ever!
Would make for an interesting game of pong!
I misread both the title and the summary. I got:
....
Simpletons bounced off orbiting satellite.
at the University of Vienna and colleagues have taken an important step fowards by bouncing this individual Anton Zeilinger off the Ajisai geodetic satellite
...
It's been a long Monday.
Ok, I can buy this.
I think we are talking about two different parts of the HUP. While you did a fine job describing the "state" of the photon, I guess I was referring to specifying the "position" of the photon. If specified tight enough to hit the mirror, the HUP effect on momentum was enough to make the error cone bigger than the mirror.
But I was also taught that the Universe was going to re-collapse and that moon craters were volcanos.
Now, either get off my lawn or help me with this Beowulf Cluster of XBox 360s!
Hemisphere-wide disco dance party everybody!!!!
\o|>
W3 h4v3 ur ph070n. F u 3v3r w4n7 70 s33 17 4g41n, u mus7 ...
Who would win this election: Andrew Weiner vs Andrew Weiner's weiner.
Why not bounce a single photon off of my perfectly shaped ass
No you haven't violated the HUP. Your experiment has something to do with observer effect but I have no clue what it is supposed to prove. However, you haven't measured the position and velocity of the particle, so you havn't violated uncertainty principle.
What if Tetris was invented by Nazis?
The observer effect is a direct result of the connection between position and velocity.
My design has determined the position of an object (within the box) without effecting the speed whatso ever since I haven't interacted with it.
Most people confuse the difficulty of measurement with the uncertainty principle. The difficulty of measurement has to do with the fact that you can't measure something without affecting it. The uncertainty principle is actually a direct consequence of the fundamental postulates of quantum mechanics. You cannot, even in principle, even as a thought experiment, construct a quantum mechanical state which violates the uncertainty principle (or any of the uncertainty principles). This is a mathematical certainty; it follows using pure logic from the postulates of quantum mechanics.
The difficulty of measurement is merely a mechanism by which the uncertainty principle is "enforced". If the postulates of quantum mechanics are correct (ie, if they are physical "law"), then the various uncertainty principles are correct (physical "law").
You might read the relevant wikipedia section for more clarification. Also, get yourself a copy of David J. Griffiths An Introduction to Quantum Mechanics, and be prepared to work through a decent bit of math. It will improve your understanding of quantum mechanics greatly.
SIGSEGV caught, terminating
wait... not that kind of sig.
The FCC is already making plans to auction off the entire spectrum of quantum communications for billions of dollars.
I will continue to follow this with interest.
LedgerSMB: Open source Accounting/ERP
Say you create a polarized single photon. Any measurement of that photon will destroy it, and no single measurement will allow you to fully characterize it's polarization state. This is the foundation of Quantum Key Distribution (QKD). If somebody were to try to eavesdrop, she would have to intercept single photons and measure them, thereby destroying them. She could send new photons to replace the ones she measured, but enough would differ from what was originally being sent that the people trying to create a secure key would know there was an eavesdropper.
The experiment in the linked article operates by sending pulses containing on the order of 10^16 photons, all in the same state. An eavesdropper could simply intercept some of those photons and pick up the key without anyone knowing. In order for this setup to work with QKD, they would have to *send* single photons from the very beginning.
They claim 4.6 clicks per second in this experiment. If they sent single photons, that would come out to around 4.6 * 10^-16 clicks per second. This would be nigh undetectable with the dark counts they have, but let's assume dark counts weren't an issue. Pulsing at 17KHz would mean they could get 7.82 * 10^-11 bits of key per second. That translates to around 500 000 years to exchange a 128-bit key. That's not very practical.
Now, I really don't mean to bash them. Just aligning a satellite and getting any results at all is impressive. While what they have is not practical for actual QKD, the seed of innovation is there. Exciting stuff!
Oh wait ...
Gentoo Linux - another day, another USE flag.
Finally a novel use of the word 'Ping' We pinged the moon. Of course a trace route is trival since its basically line of sight.
Of course Richard Feynman thought of light as nothing more than particles, that behaived as summations of particle paths called path integrals. Q.E.D. is based upon that.
Take out a CD. Look at the rainbow. Q.E.D. proved.
I knew Einstien personally...er.. Hans... his son.
...for some brief entanglement and possible spooky action. Strangeness and charm a definate plus. Let's take a spin and hit the disco ball together. Must accept me for who I am - interfering observers need not apply. Will give you my specifics when you give me yours.
[The scientists couldn't send paired photons; they're too intimately entangled.]
The Wolfpack Project: BitCoin + Crowdfunding = Political Accountability
Actually, if you review the uncertainty principle, you find that uncertainty includes more than just position and velocity but in the quantum world it also includes entanglement with the environment. Having entangled particles adds a great deal of uncertainty since you don't know what the other particel in the pair is experienceing.
This is actually Bohr's solution to one of Einstein's thought experiments, although phrased differently. (Read up on the light in the box)
Therefore, you are partially correct. I was clumbsy with my terminology. The HUP allows for an elimination of the observer effect. Therefore you can determine both the position AND velocity to an arbitraily high percision by increasingly entangling it with the universe.
In this way, my device COMPENSATES for the HEISENBERG uncertainty principle. It is a Heisenberg Compensator.
What does this mean? Honestly I don't know. I first ran across this experimental design in a Scientific American article about 15 years ago. I have seen references to it since then but never researched it more extensivly. With my 2 years of college physics and a healthy interest in applies quantum phsyics hobbies, I would guess that after measurment the particle will have an increase in the level of randomness. In addition, the amount of energy will increase exponentially, increasing the entropy in the universe to compensate.
But IANAP and my guess should be taken with a large grain of salt.
Instead of wasting time developing this quantum nonsense, we need to find a way to send an avian carriers around the globe in the time it takes a photon to bounce off a satellite.