On Tue, Dec 03 2013, Jim Bell wrote:
Okay, thank you for clarifying this matter. I merely Google-searched for 'EDFA quantum entanglement' and found and cited this paper, and that only because it referred to the problem of trying to amplify quantum signals through an EDFA.
No problem. Not having read the actual paper, I'm not even sure what they meant by "noise" preventing amplification of quantum signals in an EDFA. Quantum states cannot be copied, which seems like a more fundamental problem, but perhaps they are talking about the potential for using an EDFA just to create a large number of entangled particles.
Myself, I am hoping that longer-key public-key cryptosystems will remain unsolved by quantum techniques, at least as long as it takes to get rid of governments. After that, it probably won't matter. As of now, it looks like things will go the way I'd like.
I'm fairly optimistic for a couple of different reasons. First of all, progress on quantum computers has been very slow and the experts in the field who have spoken up believe it's unlikely the NSA has a major breakthrough on this front. Second, I'm skeptical that quantum computers can even be made to work at all. While D-Wave and others have built systems that they *believe* are quantum computers and shown some evidence that they behave as one would expect for such devices, nothing has yet been demonstrated that could not easily been achieved with a classical computer, though much of this is due to the small scale of the devices. Even if quantum computers can be made to work, one can hope that by then we'll either have quantum cryptography infrastructure in place (though the need for physical infrastructure scares me here - maybe guerrilla wireless quantum crypto?) or have widespread access to practical quantum-proof public-key crypto. Maybe either the NTRU patent will have expired or we'll have found alternative cryptosystems that do not infringe, ala the Lucas sequence alternative to RSA. Of course, the patent is only a problem in the US and its satellite states anyway. -- Sean Richard Lynch <seanl@literati.org> http://www.literati.org/~seanl/