Quantum Crypto utilizes pairs of correlated photons, so we can't be talking about an optical amplifer.
So since I've been away from the literature for a while, is there a device that can repair a deteriorating, about-to-be-collapsed superposition state? I can't see how this could occur without the requirement of acting on the other (correlated) photon either, and if that photon is physically removed from the first, then forget about it. (Though theoretically I think I can conceive of the possibility of two "correlated quantum repeaters" exchanging 'information' (including gating) about the photon pair they are collectively handling*, but no way that can be useful commerically.)
*: This isn't quite as farfetched as it seems: Even 5 to 10 years ago it was shown that there can be quantum Forward Error Correction, and simple devices were demonstrated in the laboratory.
-TD
From: Bill Stewart <[EMAIL PROTECTED]> To: "Tyler Durden" <[EMAIL PROTECTED]> CC: [EMAIL PROTECTED], [EMAIL PROTECTED] Subject: RE: QC Hype Watch: Quantum cryptography gets practical Date: Fri, 01 Oct 2004 11:59:40 -0700
At 05:12 PM 9/30/2004, Tyler Durden wrote:
What's a "quantum repeater" in this context?
It's also known as a "wiretap insertion point"...
> As for "Hype Watch", I tend to agree, but I also believe that Gelfond > (who I spoke to last year) actually does have a 'viable' system. > Commerically viable is another thing entirely, however.
"Practical" implies that there's a crossover point between cost and benefit and that implementation is on the "benefit" side.
Implementation may now be possible, and the costs may be lower than their previous infinite value, but the main benefits I see are public relations hype to impress the rubes and protect against zero-day exploits against Diffie-Hellman or Cisco IOS. But you could protect against the Cisco exploits just as easily with a conventional-key encryption hardware box, and you wouldn't need contiguous fiber.
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