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First Secure Quantum Crypto Network Up and Running
John Lam was one of many readers to send in news that on Thursday, "at a conference in Vienna, Austria, as reported by the BBC, a European Community science working group built a quantum backbone using 200-km of standard commercial optical fiber running among seven sites and successfully demonstrated the first secure quantum cryptographic key distribution network. In addition, each of the seven links used a different kind of quantum encryption, demonstrating interoperability between the technologies. To paraphrase, the project focused on the trusted repeater paradigm and developed an architecture allowing seamless integration of heterogeneous quantum-key distribution-link devices in a unified framework. Network node-modules managing all classical communication tasks provide the underlying quantum devices with authentic classical channels. The node-module architecture uses a layered model to provision network-wide, end-to-end, provably secure key distribution."
http://en.wikipedia.org/wiki/Quantum_teleportation
You'll be able to tell if your web traffic has been snooped by the authorities because all your lolcats will arrive dead!
Under DARPA sponsorship, and together with our academic colleagues Harvard University and Boston University, BBN Technologies has recently built and begun to operate the world's first Quantum Key Distribution (QKD) network. The DARPA Quantum Network employs 24x7 quantum cryptography to provide unprecedented levels of security for standard Internet traffic flows such as web-browsing, e-commerce, and streaming video.
The DARPA Quantum Network became fully operational on October 23, 2003 in BBN's laboratories, and has run continuously since.
source: http://bbn.com/technology/information_security/quantum_cryptography
You know, Star Trek is fiction, right? Not all the technology in the Star Trek fictional universe is possible, an some others will come out very soon others probably never.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
it's only Photons that have been 'tele-ported'
It is actually not a particle like a photon, but only information that is teleported. Just in case your next question is "doesn't this mean we can communicate at the speed of light?" you must have a classical information channel as well in order to make sense of the teleported information.
xkcd is almost always relevant
Wanted: Schrödinger's Cat. Dead and alive.
More like: to make the subject even more unintelligible...
I heard something about this on the radio last night (wasn't paying full attention).
But they were talking about quantum key exchange. Assuming that they're then using a standard symmetric key to encrypt the link it's still theoretically breakable, just the key exchange that isn't.
If they're quantum encrypting all the data then that's pretty astonishing - they were talking about video-conferencing so they need a reasonable bit rate and the fidelity rate has to be above 5/6[1] otherwise the link might be vulnerable to a quantum cloning attack.
[1] Assuming the best attack is a universal quantum cloning machine. The maximum theoretical fidelity isn't known for most non-universal quantum cloning machines (but is trivially known for some - e.g. 3/4 for a naive measure and retransmit). I don't know whether it's possible to prove that the 5/6 is a sufficient lower bound on the fidelity.
Tim.
God said, "div D = rho, div B = 0, curl E = -@B/@t, curl H = J + @D/@t," and there was light.
So, we have quantum computers with quantum networks doing quantum cryptography. What's next, buying music with quantum DRM, i.e. the song is both there and not there until the sound card observes it? ;)
..." trusted repeater paradigm "...
Okay, so basically you're only 'secure' up to about 30 miles, and that's only if you have a real, honest to goodness, point to point fiber link. Otherwise they're still converting photons to electrons, and making new photons, at the repeaters.
It's no more secure than current fiber, except that you've limited the attack vector and locations to known points, namely the repeaters.
Yeah, but the same crypto that allows digital signatures also allows secure key exchange.
In other words, although this is an impressive achievement, it isn't clear to me that there's any practical application as yet. Particularly when we consider that modern crypto is almost certainly secure, so that intercepting the bits en route is pointless, and that you don't need crypto over a physically secure route.
Quantum computation and communications may well be very useful some year, but 2008 isn't it.
"When you have eliminated the unacceptable, whatever is left, however improbable, must be the truthiness" - Holmes
Quantum key distribution (QKD) relies on the fact that a single measurement can only reveal partial information about its state. i.e. The same fundamental physical property that makes QKD work also makes it impossible to "read" a photon at a trusted repeater station and then resend an identical copy. This would violate the "no cloning" theorem. Instead, the trusted repeater would have to exchange a key with both the sender and receiver. This obviously requires trust and slows things down, but it's not unreasonable in a European bank network where many banks that both trust each other are physically located within a short distance of each other. (Current QKD is limited to links of distances of about 150 km due to loss in fiber, and the secret key bitrates at these distances are not good.)
End point to end point QKD is possible with what are called quantum repeaters. In this scheme, the repeater station creates single photon pairs and sends them to the adjacent links in the chain. At each link, bell state measurements are performed that create a daisy-chain of entanglement swapping until, ultimately, the sender and receiver at the two ends of the chain are left with an entangled pair that they can use to create a key. In this scheme, the repeaters actually gain no information about the entangled pair that the sender and receiver wind up with, and the sender and receiver are able to detect tampering just as they can with other forms of QKD. The result is a repeater network over which secure communication is possible even if the repeaters are untrusted. The worst case scenario, theoretically, is that the eavesdropper just cuts the line so that communication isn't possible.
This technology works experimentally, but will not be practical until quantum memory (i.e. light storage) becomes practical. The problem is that, without memory, each link in the entanglement chain has to receive photons at the same instant in time. With loss happening randomly in all the links, the probability of this happening is no greater than the probability of a photon traveling directly from the sender to the receiver. Ergo, you gain nothing.
Quantum memory is a hot field of research and several experimental groups have shown promising results using a variety of approaches. In short, QKD will not be limited to trusted relay networks for long.
No, xkcd is always almost relevant.