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Theoretical Breakthrough For Quantum Cryptography
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."
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!
Especially when dealing with entangled triplets.
cute tits or quit its?
Paying taxes to buy civilization is like paying a hooker to buy love.
Someone please correct me if I'm wrong here, and I haven't had time to read the entire article, but wouldn't this also bypass the conventional data transmission necessity for quantum communications?
I think this is engineering, not theory. Theory was the original idea of using entanglement for cryptography. Now they're applying the technology to make it practical, and that's engineering. They're adding a bit of steel or another entanglement to make it more usable. If nobody has built this device yet, it's theoretical engineering.
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?
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.
#fuckbeta #iamslashdot #dicemustdie
"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?
Technoli
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.
Glap glar photons biddle doo-vack triple photon vajmu double photon zirreyzoo-zah picture frame powlat pweegoo paparazzi photos of Alice and Bob.
Sorry about the mess.
Why cant they simply open a sub space channel and use a Tachyon pulse to synchronize the two frames ?
Somehow saying the one tends to get the other in response anyway...
I, for one welcome our new quantum overlords.
... quantum parity!
cute tits or quit its?
Both obviously!
Yes.
Oh... so that's what the kids are calling it these days... ??
Maybe I'm not up on my vocab as of late, but since when does the phrase "Theoretical Breakthrough" make any kind of sense?
They are working on developing a communication technology that would allow one absolute proof that nobody is listening in. (if anyone tried to listen in, it would always be detectable.) You don't think that there are vast applications for such a technology?
As Howard Tayler of Schlock Mercenary notes,
Do I need to use smileys or [/joke] ubbcodes in every post?
Yes. You do. In every post.
Slashdot social media options: AIM, ICQ, Yahoo, Jabber and Mobile Text. Why no MySpace?
I just KNEW there was a third guy involved in there. Bob was never going to satisfy Alice all by himself, all these years.
Religous speak to God. Insane are spoken to by God. When all shut up, one can finally hear Shostakovich in peace
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 (for example rgb(125,54,74)) - and the copy you make will again be spread over the different frequencies in a random way. So some of it will only be visible again if it is viewed under light of color rgb(245,45,7), while other parts can only be seen under light rgb(45,4,48) So the end result of your copy will NOT be the original. When Alice wants to read the letter, she uses the frequency that Bob told her to use. If that color wasn't rgb(125,54,74), then Michael wasn't able to copy the message anyway. But even if Michael already used the correct color to make the copy, the copied version will only have part of the message in the correct color. So Alice uses rgb(125,54,74), and then notices that most of the words on the letter are still missing! En thus she knows that this is not the original one, but a copy!
(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 (for example rgb(125,54,74))
- and the copy you make will again be spread over the different frequencies in a random way.
So some of it will only be visible again if it is viewed under light of color rgb(245,45,7), while other parts can only be seen under light rgb(45,4,48)
So the end result of your copy will NOT be the original.
When Alice wants to read the letter, she uses the frequency that Bob told her to use. If that color wasn't rgb(125,54,74), then Michael wasn't able to copy the message anyway. But even if Michael already used the correct color to make the copy, the copied version will only have part of the message in the correct color.
So Alice uses rgb(125,54,74), and then notices that most of the words on the letter are still missing! En thus she knows that this is not the original one, but a copy!
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.
entropy happens
So, this works for Alice and Bob. What about Homer and Jethro?
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.
So if this is the future...where's my jet pack?