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U.S. Department of Energy Unveils Blueprint for the Quantum Internet
- Yoric 6y agoIt's great to see fundamental research being funded. However, the title is... a tad ambitious. To the best of my understanding, the "quantum internet" so far has managed to transport 1 bit across 26 miles and it's not clear at which speed (yeah, I know it's theoretically above the speed of light, but I'm not sure about the specifics here) or which infrastructure was needed (apparently, fiber cable, in which case it's not entirely clear to me what makes this quantum).
- willcipriano 6y ago>yeah, I know it's theoretically above the speed of light, but I'm not sure about the specifics here I thought superluminal communication is considered impossible.[0] [0]https://en.wikipedia.org/wiki/Faster-than-light_communication https://en.wikipedia.org/wiki/Faster-than-light_communicatio...
- Yoric 6y agoThat would fall into the paragraph "Quantum nonlocality" of your link. At least, that's how it _could_ be. Not sure how it is actually.
- roywiggins 6y agoYou can't use entanglement per se to communicate at all: https://en.wikipedia.org/wiki/No-communication_theorem https://en.wikipedia.org/wiki/No-communication_theorem
- Yoric 6y agoI wasn't aware of this theorem, thanks!
- mhh__ 6y agohttps://quantumcomputing.stackexchange.com/questions/21/quantum-entanglement-for-faster-than-light-ftl-network-communication https://quantumcomputing.stackexchange.com/questions/21/quan... The communication relies on an exchange of information via classical means so the relativistic bound holds.
- Yoric 6y agoThanks, my bad!
- roywiggins 6y agoNo, it's not faster than light. It can't be. You have to physically pass particles around to communicate, and those move at a normal speed. https://en.wikipedia.org/wiki/No-communication_theorem https://en.wikipedia.org/wiki/No-communication_theorem All quantum cryptography does is make the photons you send tamper-evident. You can use it to establish a shared key that can't be snooped on, and then use that to communicate using ordinary symmetric cryptography. Of course, asymmetric crypto does this fine, so unless you are very suspicious of modern asymmetric crypto you probably don't need it.
- Yoric 6y agoThanks for the precisions, my bad :)
- patagurbon 6y agoThere have been quantum networks of this type for quite some time, it's just quantum key distribution as far as I can tell. It's not transmitted above the speed of light, there is no known method to do so.
- Yoric 6y agoThanks, my bad!
- PaulAJ 6y agoQuantum encryption is solving a non-problem. It provides a mechanism which guarantees that a message sent over a point-to-point optical link hasn't been intercepted. However: * It is orders of magnitude slower than normal data transmission. * The range is limited. That makes it suitable for key exchange between two switches connected by a fibre. However Diffie-Hellman key exchange does this perfectly well already, if you need it. Also quantum encryption can't survive going through any kind of forwarding other than an optical circuit switch, so as soon as you do anything higher level you need to decrypt and re-encrypt the data, breaking the physical guarantees. When you look at the security threats to modern communication, physical taps are way down the list. Security is already built on the idea that the network is compromised, so end-to-end encryption is already the norm. Adding quantum encoding buys you nothing.
- Yoric 6y agoOh, it's Quantum as in "quantum encryption" rather than "let's break the speed of information thanks to quantum entanglement"? That starts to make more sense.
- roywiggins 6y agoYou can't use entanglement on its own to signal at all, let alone sidestep the light speed limit. https://en.wikipedia.org/wiki/No-communication_theorem https://en.wikipedia.org/wiki/No-communication_theorem