Quantum Messages Travel 254 km Using Existing Infrastructure For the First Time (phys.org) 11
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
Watch it! (Score:2)
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This one's H.254 (where H is Planck's constant).
Can somebody please explain the point? (Score:2)
... 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?
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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.
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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.
This paper's main contribution (Score:2)
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.