Quantum Messages Travel 254 km Using Existing Infrastructure For the First Time (phys.org) 25
Researchers in Germany successfully demonstrated coherent quantum communications over 254 km of existing commercial telecom fiber, marking the first real-world deployment of such a system without cryogenic cooling. Phys.Org reports: Their system uses a coherence-based twin-field quantum key distribution, which facilitates the distribution of secure information over long distances. The quantum communications network was deployed over three telecommunication data centers in Germany (Frankfurt, Kehl and Kirchfeld), connected by 254 km of commercial optical fiber -- a new record distance for real-world and practical quantum key distribution, according to the authors. This demonstration indicates that advanced quantum communications protocols that exploit the coherence of light can be made to work over existing telecom infrastructure. The research has been published in the journal Nature.
Not instantaneous communication, alas (Score:2)
https://thequantuminsider.com/2023/02/20/quantum-entanglement-communication/#:~:text=Even%20so%2C%20though%20quantum%20particles,transmit%20data%20usin
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Or fortunately. Because if FTL communication was possible, basically all of quantum mechanics becomes invalid and so do the "secuerity" guarentees. Which are false anyways.
Watch it! (Score:5, Funny)
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This one's H.254 (where H is Planck's constant).
Re: Watch it! (Score:3)
Can somebody please explain the point? (Score:3)
... with a concrete example.
So you are talking to a remote person. All you need is a pre-shared key in order to exchange session keys.
If you don't have any pre-shared key, then how on earth can you authenticate? How do you know you are doing Quantum key distribution with the right person?
Surely it is only resistant to MitM attacks if you trust the endpoint. And by what method can you trust the authentication, which does not also provided easier session key exchange than Quantum Buzzwords?
What is the purpose of the tech, aside from raising more funding for research?
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Re:Can somebody please explain the point? (Score:4, Informative)
Sorry my friend, but nobody here has the slightest idea how entanglement works, let alone quantum physics.
Well, I have a *slight* idea. Entanglement is a property of QM, which is a model. Mathematically we know exactly how it works. And it makes predictions that match observations. It's only confusing (very!) if you start asking what is happening under the hood with reality.
Nevertheless, the idea is that, traditionally, even the best encryption does not guarantee that the message hasn’t been intercepted. By using quantum entanglement, the recipient of the message is guaranteed that it has not been intercepted (or, conversely, that it has been).
You can get the same result by using a one-time pad. Anybody intercepting just sees random noise. And you can embed it in continuous random noise so they don't even know when you are communicating. QKD seems a whole lot more effort. Distributing a terabyte pad (say a TF card) is just as easy as distributing a single token for authentication.
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In some cases,it can be decoded.
When used incorrectly, sure. But OTPs are provably secure when used correctly (i.e. not reusing the keys, as happened in ww2)
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The prerequisites that make OTPs provably secure cannot be realized universally, they require very strong levels of privacy, physical security, and fidelity of transmission at least.
For example the transmissions could be jammed, the user could be physically attacked, or could be constantly monitored by cameras etc. These things happen in wars and peace.
I would agree with the statement "in ve
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'not reusing the keys,'
SO it wasn't a OTP...
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A one-time pad communication can be intercepted. In some cases,it can be decoded. It happened in WWII. It can happen today.
It was possible because humans are broken and kept picking values they felt favourable toward when generating the pads. The process had the "appearance" of randomness but it was not. This is nowhere near the same thing.
Nothing defeats a one-time pad that is generated using a sufficient degree of randomness, with the exception of quantum compute that could, technically, drunk-walk itself through the space until it produces results that are not gibberish.
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Regarding drunk-walking / brute forcing: Doing it with any computer, quantum or not, will produce *all* non-gibberish texts of the message length with equal probability. So you have no idea if what you found was actually the cleartext message. At least given that the one time pad is used correctly, as you say.
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Untrue. All practically deployed mechanisms for this have been broken. So, no, you do not get these guarantees.
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It is supposed to protect against eavesdropping assuming the channels aren't MitM'd (it uses a quantum and classical channel).
So more a defense in depth than completely replacing classical cryptography, theoretically. Practically it's way too much effort for too little gain, a boondoggle.
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If you don't have any pre-shared key, then how on earth can you authenticate? How do you know you are doing Quantum key distribution with the right person?
From everything I've read about QKD... you don't. There is nothing about quantum physics that can distinguish friend from foe. You need an authenticated channel, done with a pre-shared key, before you can begin quantum key distribution, end of story.
The only real interesting thing about this specific article is that they used "practical" single-photon detectors instead of cryogenic equipment.
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There is no point. This stuff is insecure (in practice) and has abysmally bad properties otherwise. Just use conventional encryption and do it right. This is just another bad idea that refuses to die.
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The point is secure key transmission and communications using ordinary commercial equipment already installed out there.
Quantum key distribution doesn't require use of an algorithm to generate the key stream - with adequate bandwidth you can use one-time pads that are basically communicated down the same channel.
If someone taps the channel to steal the key, it can be detected unless the tapper is extremely lucky.
Basically it boils down to this, let's use light polarization. I can send light down an optical
This paper's main contribution (Score:4, Informative)
Existing methods for coherence-based quantum key distribution rely on ultra-stable optical cavities and cryogenic photon detectors, which limit scalability and practical deployment.
This study replaces that setup with a non-cryogenic, scalable system using off-band phase stabilization and commercial telecom infrastructure, yet still achieves 254 km secure key distribution, effectively doubling the practical distance for real-world QKD (according to the authors).
Re: This paper's main contribution (Score:2)
Hi folks, I didn't read the paper but this doesn't seem like quantum data transmission as I read about in the WSJ but quantum key distribution which begs the question. How large was the key?
That's great! (Score:2)
Now they just need to make it still work after someone *cough*Russia*cough*China*cough* has cut the fibre.