
U.S. Department of Energy Unveils Blueprint for the Quantum Internet - sahin-boydas
https://www.energy.gov/articles/us-department-energy-unveils-blueprint-quantum-internet-launch-future-quantum-internet
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PaulAJ
Quantum 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.

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Yoric
Oh, 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
You 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)

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Yoric
It'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).

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roywiggins
No, 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
Thanks for the precisions, my bad :)

