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Theorists Make Quantum Communications Breakthrough
KentuckyFC writes "One of the cornerstones of modern physics is Claude Shannon's theory of communication, which he published in 1948. If you've ever made a phone call, watched TV, or used a computer, you've got Shannon to thank for describing how information can be moved from one place in the universe to another using an idea called the channel capacity. But nobody has been able to develop a quantum version of this theory. So physicists have no idea how much quantum information can be sent from one point to another. Now two American physicists have made an important breakthrough by proving that two quantum channels with zero capacity can carry information when used together. That's interesting because it indicates that physicists may have been barking up the wrong tree with this problem: it implies that the quantum capacity of a channel does not uniquely specify its ability for transmitting quantum information (abstract). And that could be the idea that breaks the logjam in this area."
Actual link: http://cm.bell-labs.com/cm/ms/what/shannonday/paper.html
Now two American physicists have made an important breakthrough by proving that two quantum channels with zero capacity can carry information when used together.
So who wants to join my class-action lawsuit against math teachers?
"two quantum channels with zero capacity can carry information"
Feynman once said that nobody understands quantum mechanics, and this is why.
When you use quantum encryption, the theorists win !
\u262D = \u5350
It was called ISDN.
I c u d h l w t q a t m r p o r p y
h h t o n s i e g e t d a
t o l e p i h u n u c y t g a h .
RS
Shoes for Industry. Shoes for the Dead.
I'm not sure how useful this is. The summaries seem to say that if you take two or more channels that have a signal to noise ratio of zero, there's some potential for binding them into a useful channel, but there's no indication of what kind of recovery rate there can be gained from this. Is this just error-correction applied to an extreme?
Am I the only one who's worried that we keep getting 'news' from papers published on ArXiv, which is not a peer-reviewed source?
Just saying, it needs to be taken with a grain of salt.
You just got troll'd!
Oops, too late. You're entangled!
Bruce Perens.
When it comes to quantum mechanics, a theorist is not far removed from a terrorist!
Does the data really have to be copyrighted for that to work?
I think that Khashishi has got the essence of the 0+0>0 thing here. I haven't completely penetrated the noise in the Smith/Yard ArXiv article yet, but I'd bet my money that it boils down to this:
Take two channels in each of which all bits are completely random, and independent of the information that you wish to send. Let each bit of your information determine the correllation or anticorrellation of corresponding bits in the two channels, by introducing a quantum constraint between them before their actual random values are determined. Then, as in Khashishi's description, the xor of the two random channels is the message.
The only difference I detect in Smith/Yard vs. Khashishi is that they use quantum trickery to make the whole thing look symmetric. Neither of the random channels predates the other. Each one, evaluated singly, appears to be completely independent of the encoded message. In Khashishi's description, the time sequence in the construction of the two random sequences makes one of them seem a priori random, and the other to be a one-time pad encoding of the message, while in the Smith/Yard article you can't tell which is which.
It seems more like a meretricious way of telling a causal story about a well-known phenomenon than something truly "essentially quantum."
Mike O'Donnell http://people.cs.uchicago.edu/~odonnell/
I have DirecTV. That gives me something like six hundred channels which have zero intellectual capacity but yet still manage to carry data.
Harry "Hello Jim Im ringing you back regarding the message you left on my voice mail." Jim "What message ? I hevent left one yet" Harry "Aw crap I did it again, I will never get my head around our new quantum telephone system"
...and if I combine your post with a random pad of 1s and 0s, will I get something that has anything to do with TFA?
I read Usenet for the articles.
You can extract immense amounts of information from the combination of Fox News (channel 0 with no signal) and the White House Press Secretary (channel 1 with no signal).
Anything in common is a lie, and that is useful information.
You are being MICROattacked, from various angles, in a SOFT manner.
Not a S/N ratio of zero, their definition of channel capacity is only very tenuously connected to Shannon's channel capacity really. Quantum channels already have 0 capacity at non zero fidelity (the quantum equivalent to S/N). The 0 capacity channel from this paper aren't 0 capacity because of their fidelity though, the channels are 0 capacity for different reasons.
So it's not really directly applicable, "just" interesting math.