Theoretical Breakthrough For Quantum Cryptography 116
KentuckyFC writes "Quantum cryptography uses the quantum properties of photons to guarantee perfect secrecy. But one of its lesser known limitations is that it only works if Alice and Bob are perfectly aligned so that they can carry out well-defined polarization measurements on the photons as they arrive. Physicists say that Alice and Bob must share the same reference frame. That's OK if Alice and Bob are in their own ground-based labs, but it's a problem in many other applications, such as ground-to-satellite communications or even in chip-to-chip communications, because it's hard to keep chips still over distances of the order of the wavelength of light. Now a group of UK physicists have developed a way of doing quantum cryptography without sharing a reference frame. The trick is to use entangled triplets of photons, so-called qutrits, rather than entangled pairs. This solves the problem by embedding it in an extra abstract dimension, which is independent of space. So, as long as both Alice and Bob know the way in which all these abstract dimensions are related, the third provides a reference against which measurements of the other two can be made. That allows Alice and Bob to make any measurements they need without having to agree ahead of time on a frame of reference. That could be an important advance enabling the widespread use of quantum cryptography."
Stay away from this (Score:5, Funny)
One thing, with quantum crypto, the code changes when you look at it. In other words, you have to know the key before seeing it.
Two, it kills a LOT of cats! You get the code right, and BAM! dead cat.
PETA will be against this!
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You just have to wrap the secret bit-thingies in double-secret bit-thingies and before you know it's you're a tenured professor because nobody knows what the hell you're actually doing.
Just wait until he replaces the dilithium crystals with Folgers, then we'll really be in trouble.
Re:Stay away from this (Score:4, Funny)
Don't panic. Find comfort in the fact that there's a universe in which a bear brutally sodomized then killed him before he was able to push the Submit button.
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Two, it kills a LOT of cats! You get the code right, and BAM! dead cat.
I always suspected that all this "entangling photon pairs" and "quantum encryption channel" stuff was just a bunch of scientists jerking off, but I didn't think they were actually euphemisms for spanking it!
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Exactly. This is sort of why I am deeply suspicious of quantum cryptography. When is a cat not a cat? Look at your data sideways, and it suddenly realises that it's not supposed to exist?
Oh wait, that sounds like a Microsoft filesystem...
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Mmmm, sheep
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PETA == "People for the Ethical Treatment of Animals"
Its not about hate, its about recognising that animals have feelings too. If you ever had a pet you would know this of course.. Also, I just saw this comment [slashdot.org] about copyright law and the UK Pirate Party which applies to PETA just as much. You can be sure that they won't get anywhere near what they are asking for but they know that and want you to consider that already you are sitting in an unethical position. They want to and need to rub your face in it be
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qutrits? (Score:1, Offtopic)
Applying the standard naming conventions would result in qutits. I much prefer qutits.
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Especially when dealing with entangled triplets.
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cute tits or quit its?
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Somehow saying the one tends to get the other in response anyway...
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cute tits or quit its?
Both obviously!
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Applying the standard naming conventions would result in qutits. I much prefer qutits.
And the scientific community would be rather better off choosing names that let us focus on the furtherance of humanity's knowledge of the inner workings of the universe than opening the door for juvenile jokes.
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Applying the standard naming conventions would result in qutits. I much prefer qutits.
And the scientific community would be rather better off choosing names that let us focus on the furtherance of humanity's knowledge of the inner workings of the universe than opening the door for juvenile jokes.
The planet Uranus thanks you.
Everyone else thinks you're a bit too uptight.
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Hint...
This was in fact a juvenile joke.
I wasn't being serious.
Do I need to use smileys or [/joke] ubbcodes in every post?
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Do I need to use smileys or [/joke] ubbcodes in every post?
Yes. You do. In every post.
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As Howard Tayler of Schlock Mercenary notes,
Quantum Communications (Score:1, Offtopic)
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Gah drbbt.. Accidentally modded parent as redundant. Posting to remove it (was going to be insightful).
So I get marked off topic because I post a comment to remove a bad moderation I made?
The proper response should have been OverRated if you don't want everyone to see me - not OffTopic.
*Grumbles about Moderators who love power too much*
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Would this system still allow alice/bob to know if someone's evesdropped? What's the difference between a hostile evesdropper and just some other part of the infrastructure for getting data from alice to bob? Without that, quantum cryptography is just another encryption system, and there are nothing wrong with the current ones. Right? (It would arouse me if replies to this post started simply "Wrong.")
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(It would arouse me if replies to this post started simply "Wrong.")
Not to judge your lifestyle choices, but I'm pretty sure that the reason no one has replied as such has to do with the collective will of the community not to see you aroused.
Engineering (Score:3, Interesting)
Re:Engineering (Score:4, Insightful)
What makes you think that theory and engineering are mutually exclusive, with a fine dividing line?
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Re:Engineering (Score:4, Insightful)
Theory is coming up with a hypothetical mechanism for incorporating extra information so that it doesn't require a known reference frame.
Engineering is making a device that actually does it reliably.
As my sibling post said, there's no clear dividing line. But this is definitely on the theory-ish side of it.
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Now they're applying the technology to make it practical, and that's engineering.
After that, the time for the third phase - marketing and selling - will come, when patents, stupid business plans and inflated prices will make it impractical again.
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You've discovered the Quantum Theory of Engineering: If it practical enough to produce, Business School Product will screw it up into being impractical to produce. The tricky part is that if Business School Product is practical enough to produce, then Business School Product becomes impractical to produce. When this happens, a fixed point is reached and all the world's business schools go out of business because it is then recognized no one in their right mind would go into the business of building a busine
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Here's a link to the paper: arXiv:1003.1050v1 [arxiv.org]. Have a read and make a more informed opinion about what field it belongs it.
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They're adding a bit of steel or another entanglement to make it more usable.
Didn't IBM do that already in the 90's?
You lost me at hello... (Score:5, Funny)
Boy am I glad I didn't pursue that physics major. The only thing I got out of that is that Alice and Bob needed a marriage counselor to reconcile their differences.
Anyone mind converting that attempt in layman's terms to something useful, like a car analogy?
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Quantum physics does not have a car analogy. Cars cant be mixed up and then split so each part has a bit of the other, and not just physically. if one car starts, it means its parts in both entangled sets start and the moment you go and look witch of the cars you have it becomes one or another, instantly causing the other entangled car thingy to become the car you didn't get. Also, fu Eve.
Hungarian Physicists and Automotive Engineers are closer to tackling that problem:
http://tech.slashdot.org/story/10/02/24/1614245/Hungarian-Electric-Car-Splits-Into-Two-Smaller-Cars [slashdot.org]
Re:You lost me at hello... (Score:5, Informative)
I'll give it a shot.
Alice wants to get out of her car and into Bob's car. In laboratory conditions both cars are perfectly still so it's easy. Out on the freeway travelling at high speeds it's a recipe for disaster.
But these clever engineers have come up with a wonderful design for a semi-trailer that both cars can sit on while being driven down the freeway. Now Alice and get out of her car and into Bob's car for that secret rendezvous. In the middle of the freeway.
Re:You lost me at hello... (Score:4, Funny)
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Well, you have to consider that FLAG wasn't confident enough about the capabilities of their car's artificially intelligent on-board computers to recognize its driver to not require a hidden fingerprint scanner underneath its door handles as an access control.
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That's not new. The Foundation for Law and Goverment [wikipedia.org] had such a system in place almost thirty years ago. We've seen rehashed stories in /. before, but really, guys, 30 years?
That was Bonnie and Michael (yeah, we saw those furtive glances). This article is about Alice and Bob. Try to keep up.
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But these clever engineers have come up with a wonderful design for a semi-trailer that both cars can sit on while being driven down the freeway. Now Alice and get out of her car and into Bob's car for that secret rendezvous. In the middle of the freeway.
Eve hijacks the semi-trailer... shocking film at eleven.
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I use the Earth for similar purposes.
Nobody seems to care about my "I do it at 365km/s relative to the Virgo Supercluster" bumper sticker though.
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Here's my own amateur shot at it. If I'm wrong, I'm sure someone who knows better will correct me. Oh, and fuck the car analogy.
The quantum entanglement measurements will only work with two entangled photons when the velocities and accelerations of the two parties involved are the same. But if you're doing it with two objects with different motion, say a person on the ground and a satellite orbiting the earth, it won't. The satellite is in free fall and, according to general relativity, not in an accele
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The satellite is in free fall and, according to general relativity, not in an accelerated reference frame.
If you're not moving in a straight line at a constant speed, you're in an accelerated reference frame. Satellites are in orbit; there's no such thing as a straight-line orbit.
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Are you sure about that? It was my understanding that since it's free-falling in orbit that according to general relativity it was going in a straight line through space-time.
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there's no such thing as a straight-line orbit.
Find an orbit where you pass through one of the Lagrange points. While you are in the Lagrange points, you are moving in a straight line, because all accelerations cancel each other out there.
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there's no such thing as a straight-line orbit.
Find an orbit where you pass through one of the Lagrange points. While you are in the Lagrange points, you are moving in a straight line, because all accelerations cancel each other out there.
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No car analogy, but I think I summarize it a little simpler (though I am no expert).
In Quantum Cryptography it's possible to detect the presence of an eavesdropper. The eavesdropper, by the act of listening changes the transmission of the signal and is provably unable to put it right again. This is possible because of some physics mumbo-jumbo and is highly sensitive to the distances between the people involved.
As best I can make out, this research used more physics mumbo-jumbo to encode the distances betw
"This solves the problem by embedding it...." (Score:5, Insightful)
"This solves the problem by embedding it in an extra abstract dimension, which is independent of space."
Has it occurred to anyone else how UNBELIEVABLY FRIGGIN' COOL it is that a line like that shows up in an article that is talking about building an actual, physical device?
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AAAAAAAAAAAAHHHHHHHHHH!!!!!!!!!
The zombie apocalypse is nigh! RUN FOR YOUR LIFE!
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Re:"This solves the problem by embedding it...." (Score:5, Funny)
Has it occurred to anyone else how UNBELIEVABLY FRIGGIN' COOL it is that a line like that shows up in an article that is talking about building an actual, physical device?
I can vividly see the label on the unit packaging: "Dimensions: 0.45 x 0.3 x 0.25 x 1.7 m"
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Yes. Now get off my $%!$!#$% intergalactic intertube!!!
signed: your local Galactic Overlord
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Translation of summary (Score:3, Funny)
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Dangit... (Score:1, Offtopic)
I was all set to sell crypto supplies and repair services in the alternate dimension. Do you have any idea what this is going to do to housing prices there?
Just wondering .. (Score:3, Funny)
Re:Just wondering .. (Score:4, Funny)
They'd have to reroute the plasma flow and depolarise the graviton matrix first. Duh.
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Masters of the world (Score:2, Funny)
I, for one welcome our new quantum overlords.
Sound like Alice and Bob have discovered... (Score:1)
... quantum parity!
Kids today... (Score:2, Funny)
Oh... so that's what the kids are calling it these days... ??
Come again? (Score:1)
Third guy (Score:1)
I just KNEW there was a third guy involved in there. Bob was never going to satisfy Alice all by himself, all these years.
OK, Let Me Get This Straight.... (Score:1)
It's relevant to ground-based labs as well. (Score:2)
Polarization has a nasty habit of rotating when it travels through optical (telecom) fiber. To make matters worse, the degree of rotation depends on temperature and physical strain and can change quite rapidly. Of course, entangling three photons is much harder than entangling two.
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(repost, WITH paragraphs)
Apparently you missed the whole reason why quantum cryptography is radically different:
It is IMPOSSIBLE to duplicate the quantum key or the quantum message exactly.
So Michaels qubits are different from the one Bob sent AND there are ways for Alice to find out that they are different, so she knows eavesdropping has occurred.
It's a bit like making a copy of a letter
- that self destructs when it is copied or read
- that looks different depending on the light you use to scan it/read it (
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Nothing. What frame reference independence actually means is that they are encoding a reference frame in the particles themselves, so that you don't have to worry about external alignment. It does nothing about the communication channel, that does not exist through an events horizon.