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Los Alamos National Labs Has Working Hub-and-Spoke Quantum Network
New submitter hutsell writes with this excerpt from MIT's Technology Review: "Richard Hughes and his associates at the Los Alamos National Laboratory in New Mexico announced today that they have been sending perfectly secure messages with their Quantum Internet that has been in operation for the last two and a half years."
Original paper. Unlike current quantum networks that only allow point-to-point networking, the system at Los Alamos combines traditional and quantum links to route messages through a hub while retaining the security advantages of quantum networking.
Why do you think it took them two and a half years to report this? They had to make dead cat versions of every cat video on YouTube just so they could properly distribute them over the quantum network. That's a lot of dead cat videos. Your tax dollars at work.
Any word on what percentage of the quantum-encrypted traffic is flowing between classically-compromised systems?
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No, it doesn't assume the optical link can't be tapped. In fact, the quantum encoding is specifically a defense against the optical link being tapped. The data is sent one photon at a time. If a tapper captures the photon (even by leakage from evanescent waves), they destroy the information --- and are neither able to know for themselves, or reliably re-send to the receiver, the bit that was sent. If the tapper doesn't capture the photon, they they haven't tapped the line. At the receiving end, getting too high a dropped bit rate (or scrambled nonsense bits) lets you know the line is compromised, while the attacker still doesn't get any useful information.
So as long as the hub is secure, then the network should also be secure.
This destroys the protection from wiretapping that quantum crypto promised.
Well, I see two potential problems with transmitting quantum crypto through hubs without trusting them:
1. The signal loss problem. The longer the continuous link without retransmission, the more data loss and the lower effective transmission rate. What you refer to might help with that if it allows signals to be boosted without destroying/recreating the photons.
2. The routing problem. Each packet has to get to the right destination, but if every photon on the line is a quantum encryption bit then you can't read them to determine their destination without disrupting the link. I see two potential solutions here:
2.1. One is to use channels (like the old POTS approach) - you have 10 data lines and a control line to the hub, and you ring up the hub and ask for one of them to be connected to some remote destination. Then the entire network creates a single dedicated channel where photons can traverse untouched.
2.2. The more optimal approach would be packet switching, but you'd need to have packets that include both unencrypted headers (at least a destination field) and encrypted payload, and the timing/etc would have to be such that the switch can pick out only the photons it should intercept and let the rest pass through. For that matter it would require some kind of tap that lets selected photons pass through completely untouched and perfectly captures others, and that this could be switched between both modes VERY quickly.
If you can trust the hubs then you only have point-to-point links and you don't have to mess with any of this stuff. This does rely on owning all the hubs and securing them. For a big company that isn't a problem, but for a consumer you're not going to be able to own all the hubs between yourself and your bank.