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more on Could freezing light negate Quantum cryptography?
From: David Farber <dave () farber net>
Date: Sat, 5 Aug 2006 08:05:49 -0400
Begin forwarded message: From: Vadim Antonov <avg () kotovnik com> Date: August 4, 2006 10:36:24 PM EDT To: David Farber <dave () farber net> Cc: ip () v2 listbox com Subject: Re: [IP] Could freezing light negate Quantum cryptography?
Dave, This month's IEEE Spectrum article : http://www.spectrum.ieee.org/ aug06/4252 to my very amateur mind raises questions about the viability of quantum cryptography. If a photon can be frozen (and I can't say whether their technique can be extended to the photon level) can it be measured in its frozen state? That would make the difference. Richard Outerbridge
No, there's so-called "no cloning" theorem, which basically says that quantum state cannot be cloned. The act of reading quantum information destroys it, so it merely shifts to the new place. The photons are not really frozen - they are absorbed by atoms, and their state is recorded in the quantum state of atoms. Then, when conditions change, they are re-emitted. As particles, photons have no mass - meaning they cannot move slower than the speed of light. Regards, --vadim ------------------------------------- You are subscribed as lists-ip () insecure org To manage your subscription, go to http://v2.listbox.com/member/?listname=ip Archives at: http://www.interesting-people.org/archives/interesting-people/
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