• Quantum Object Teleported 100 Kilometers by Chinese Scientists
    59 replies, posted
[quote] Teleportation is the extraordinary ability to transfer objects from one location to another without travelling through the intervening space. The idea is not that the physical object is teleported but the information that describes it. This can then be applied to a similar object in a new location which effectively takes on the new identity. And it is by no means science fiction. Physicists have been teleporting photons since 1997 and the technique is now standard in optics laboratories all over the world. The phenomenon that makes this possible is known as quantum entanglement, the deep and mysterious link that occurs when two quantum objects share the same existence and yet are separated in space. Teleportation turns out to be extremely useful. Because teleported information does not travel through the intervening space, it cannot be secretly accessed by an eavesdropper. For that reason, teleportation is the enabling technology behind quantum cryptography, a way of sending information with close-to-perfect secrecy. Unfortunately, entangled photons are fragile objects. They cannot travel further than a kilometre or so down optical fibres because the photons end up interacting with the glass breaking the entanglement. That severely limits quantum cryptography's usefulness. However, physicists have had more success teleporting photons through the atmosphere. In 2010, a Chinese team announced that it had teleported single photons over a distance of 16 kilometres. Handy but not exactly Earth-shattering. Now the same team says it has smashed this record. Juan Yin at the University of Science and Technology of China in Shanghai, and a bunch of mates say they have teleported entangled photons over a distance of 97 kilometres across a lake in China. That's an impressive feat for several reasons. The trick these guys have perfected is to find a way to use a 1.3 Watt laser and some fancy optics to beam the light and receive it. Inevitably photons get lost and entanglement is destroyed in such a process. Imperfections in the optics and air turbulence account for some of these losses but the biggest problem is beam widening (they did the experiment at an altitude of about 4000 metres). Since the beam spreads out as it travels, many of the photons simply miss the target altogether. So the most important advance these guys have made is to develop a steering mechanism using a guide laser that keeps the beam precisely on target. As a result, they were able to teleport more than 1100 photons in 4 hours over a distance of 97 kilometres. That's interesting because it's the same channel attenuation that you'd have to cope with when beaming photons to a satellite with, say, 20 centimetre optics orbiting at about 500 kilometres. "The successful quantum teleportation over such channel losses in combination with our high-frequency and high-accuracy [aiming] technique show the feasibility of satellite-based ultra-long-distance quantum teleportation," say Juan and co. So these guys clearly have their eye on the possibility of satellite-based quantum cryptography which would provide ultra secure communications around the world. That's in stark contrast to the few kilometres that are possible with commercial quantum cryptography gear. Of course, data rates are likely to be slow and the rapidly emerging technology of quantum repeaters will extend the reach of ground-based quantum cryptography so that it could reach around the world, in principle at least. But a perfect, satellite-based security system might be a useful piece of kit to have on the roof of an embassy or distributed among the armed forces. Something for western security experts to think about.[/quote] [url]http://www.technologyreview.com/blog/arxiv/27843/[/url] Darn chinese and their superior scientist!
[QUOTE=News]Something for western security experts to think about.[/QUOTE] Why do people say stupid shit like this.
[quote]The phenomenon that makes this possible is known as quantum entanglement, the deep and mysterious link that occurs when two quantum objects share the same existence and yet are separated in space. [/quote] I've even read up on this and it still blows my mind every single time I read about it.
Do we break causality yet?
[QUOTE=FalconKrunch;35924209]I've even read up on this and it still blows my mind every single time I read about it.[/QUOTE] Mass Effect tried to teach me
[QUOTE=FalconKrunch;35924209]I've even read up on this and it still blows my mind every single time I read about it.[/QUOTE] I don't find it that hard to comprehend. There's a certain point where applying logic to it just stops working because this shit genuinely happens, so it's not like you can argue with it. Basically, the key to quantum physics, as I understand it, is "I don't fucking know, just roll with it."
[QUOTE=Thom12255;35924221]Mass Effect tried to teach me[/QUOTE] Mass Effect got it wrong: you can't communicate with it. (this would count as sending information instantly - a violation of causality).
[QUOTE=BrainDeath;35924260]Mass Effect got it wrong: you can't communicate with it. (this would count as sending information instantly - a violation of causality).[/QUOTE] Which we need to violate, like, hard. She's a boring and unforgiving bitch.
[QUOTE=Awesomecaek;35924289]Which we need to violate, like, hard. She's a boring and unforgiving bitch.[/QUOTE] But you can't.
[QUOTE=Cone;35924248]Basically, the key to quantum physics, as I understand it, is "I don't fucking know, just roll with it."[/QUOTE] But that just the thing, I can't, I don't like it when shit happens without an explanation. Quantum Physics breaks all rules of regular physics, yet it works. Quantum entanglement is weird on two fronts, first, two objects are [B]exactly[/B] the same and somehow connected, second, the changes that happen with one of the objects happen to the other one instantaneously and that just creeps me the fuck out.
I read once that quantum cryptography isn't actually useful for secure communications, since all it can really tell you is whether the channel is being eavesdropped or not, you still have to use classical encryption for your information (And it's a pain to setup) That said, the ability to know if a channel is being eavesdropped is super useful for secure key exchange. If you know nobody is intercepting your communications it's a perfect way of exchanging keys, which can then be used for classical encryption via normal means.
[QUOTE=Killuah;35924330]But you can't.[/QUOTE] People said that the world was flat once too. Maybe we'll discover that this as well is not entirely true as we had believed.
How credible is this source? A lot of "record-breaking" stories like this end up being bullshit.
[QUOTE=T3hGamerDK;35924396]People said that the world was flat once too. Maybe we'll discover that this as well is not entirely true as we had believed.[/QUOTE] I'm pretty sure we've tried violating the laws of the universe and it didn't work, cause they're like laws, and not like rules.
[QUOTE=FalconKrunch;35924345]But that just the thing, I can't, I don't like it when shit happens without an explanation. Quantum Physics breaks all rules of regular physics, yet it works. Quantum entanglement is weird on two fronts, first, two objects are [B]exactly[/B] the same and somehow connected, second, the changes that happen with one of the objects happen to the other one instantaneously and that just creeps me the fuck out.[/QUOTE] That thing "happening" is an interpretation. The math gives us "If I measure this photons Absolute Spin-Impulse as a, then the z-Axis spin impulse of the other photon must be b(mind you are measuring different, yet related impulses) Interpreting this as "it happens to the system" is ... how do I put it... You and your friend are blinded, you face the sky, your friend faces the street. Now you take your blinding off and you see: It rains. Now once blind you had two possibilities: Rain or no rain. By you seeing the rain, your friend WILL see the street is wet. By you seeing NO rain, your friend WILL see the street is dry. So you see: before looking(we assume) you had no way of seeing the rain or the street, but that doesn't make it "HAPPEN" to the rain or the street. Of course we assume here that there is no other way to make the street wet. That "you make it happen by looking" is a weird concept and even I(Bachelor Physics) don't 100% agree with it. At the same time you could say that everything that is possible in the universe is happening behind your back until you are looking over your shoulder and make it collapse to your reality.
What's next? China teleports their army into white house?
[QUOTE=Jacam12SUX;35924420]How credible is this source? A lot of "record-breaking" stories like this end up being bullshit.[/QUOTE] That's the paper, and that's the research they've done. [url]http://arxiv.org/pdf/1205.2024v1.pdf[/url]
[QUOTE=T3hGamerDK;35924396]People said that the world was flat once too. Maybe we'll discover that this as well is not entirely true as we had believed.[/QUOTE] Yes but people were following a stupid, religious indoctrination when saying so when every sailor could tell you otherwise by looking at the horizon. There is a difference between conclusions coming out of wrong expositions(because they are always right, logically speaking) and conclusions coming from observable facts.
[QUOTE=Swebonny;35924456]That's the paper, and that's the research they've done. [url]http://arxiv.org/pdf/1205.2024v1.pdf[/url][/QUOTE] Thanks, I'm skeptical to believe things like this lately. This is pretty incredible.
[QUOTE=TheDecryptor;35924389]I read once that quantum cryptography isn't actually useful for secure communications, since all it can really tell you is whether the channel is being eavesdropped or not, you still have to use classical encryption for your information (And it's a pain to setup) That said, the ability to know if a channel is being eavesdropped is super useful for secure key exchange. If you know nobody is intercepting your communications it's a perfect way of exchanging keys, which can then be used for classical encryption via normal means.[/QUOTE] You still need to compare observations. So if someone is manipulating both, your information channel AND your comparison channel, you are at the point where it's useless. What it essentially gives you is a second channel that needs to be broken.
[QUOTE=Killuah;35924457]Yes but people were following a stupid, religious indoctrination when saying so when every sailor could tell you otherwise by looking at the horizon. There is a difference between conclusions coming out of wrong expositions(because they are always right, logically speaking) and conclusions coming from observable facts.[/QUOTE] But we must not forget that even observable facts can change depending on the observer and the variables taken into conclusion. Thats' why theories like quantum theory can exist today, is because we find new evidence of new stuff, and as such, our theories must adapt. All I'm saying is, that it is not unlikely that even though we've observed what we've observed, does not mean that we may be looking at things the wrong way, and in some time in the future, someone will observe things in a different way and realize that a lot of things were wrong.
[QUOTE=T3hGamerDK;35924486]But we must not forget that even observable facts can change depending on the observer and the variables taken into conclusion. Thats' why theories like quantum theory can exist today, is because we find new evidence of new stuff, and as such, our theories must adapt. All I'm saying is, that it is not unlikely that even though we've observed what we've observed, does not mean that we may be looking at things the wrong way, and in some time in the future, someone will observe things in a different way and realize that a lot of things were wrong.[/QUOTE] That is not the scientific way of thinking. You are basically saying "and then some magic happens and everything is changed". No. We are at a point where, within our known and expected bonds, our theories can't be disproven. Relativity doesn't disprove Newtons laws, it just limits their applications, in fact, Newtons laws are a special outcome of Relativity. New theories will and can not disprove our old theories, they will only expand them. Better word: engulf. What you mean when you say "we might be looking at things differently in the future" is already "we might interpret things different" and that is also not scientific.
why does something tell me it's fake.
[QUOTE=J!NX;35924554]why does something tell me it's fake.[/QUOTE] [QUOTE=Swebonny;35924456]That's the paper, and that's the research they've done. [url]http://arxiv.org/pdf/1205.2024v1.pdf[/url][/QUOTE] You can try to replicate it. z
[QUOTE=Swebonny;35924586]You can try to replicate it. z[/QUOTE] Now if only I had the time and money and knowledge. :v:
[QUOTE=Killuah;35924330]But you can't.[/QUOTE] Just like you can't fly, and like you can't break the speed of sound, you can't leave the atmosphere? Like you can't transform one element into another, and like atoms are elementary, and protons and neutrons are elementary, as well? There are always scientifically sound theories for why is something impossible, until somebody proves them wrong.
[QUOTE=Killuah;35924477]You still need to compare observations. So if someone is manipulating both, your information channel AND your comparison channel, you are at the point where it's useless. What it essentially gives you is a second channel that needs to be broken.[/QUOTE] But if the attacker is messing with the quantum channel you're using to exchange keys you'd be able to detect it, and if they're messing with the normal channel you'd be able to detect that by seeing that the data fails to decrypt. And reading up about this, what I'm describing is quantum key distribution, not normal quantum cryptography (although QKD is a part of it). And apparently there's already products available exploiting it. [url]http://en.wikipedia.org/wiki/Quantum_key_distribution[/url]
Don't you have to break the speed of light to break causality? since information moves/propogates at the speed of light.
information can't travel faster than light, this doesn't break causality
[QUOTE=Awesomecaek;35924688]Just like you can't fly, and like you can't break the speed of sound, you can't leave the atmosphere? Like you can't transform one element into another, and like atoms are elementary, and protons and neutrons are elementary, as well? There are always scientifically sound theories for why is something impossible, until somebody proves them wrong.[/QUOTE] Those are all practical examples, a matter of technology, not theory. And the second row is observation. I don't know much about quantum physics but isn't causality a purely logical concept? As in, it can't be disproved because, by logic, it's already right?
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