Scientific American on Quantum Encryption

Eugen Leitl eugen at
Thu Jan 20 07:59:00 PST 2005

On Thu, Jan 20, 2005 at 10:47:38AM -0500, Trei, Peter wrote:

> I've actually seen these devices in operation. The thing
> that impressed me most was that the path need not be a
> single fiber from end to end - you can maintain quantum
> state across a switchable fiber junction. This means

Very impressive. If they manage to keep the entanglement all the way up to
LEO by line of sight it would be even more impressive
(anyone thinks this can be done at all?)

> you are no longer limited to a single pair of boxes talking to
> each other.

What makes it very important is early beginnings of practical quantum
computing. Will photonics and spintronics in solid state at RT play well with
each other? Will error correction scale to large qubit register sizes? Will
the algorithm space be large and rich enough to be practical? All very
interesting questions Scientific American fails to raise.

> True, the SciAm article doesn't address a lot of issues,
> but the fact remains that this technology is interesting
> and important.

I agree that this technology is interesting and important, but not for what
it claims to be used for. Quantum encryption right now is a tool to milk the
gullible, and hence very much crypto snake oil.

For these distances one-time pads by trusted couriers would seem so much more
practical and so much cheaper.

Eugen* Leitl <a href="">leitl</a>
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