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From: Sean Lynch <seanl@literati.org>
To: Jim Bell <jamesdbell8@yahoo.com>
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.

I am limited by the fact that I have only had a couple of classes which touched upon quantum physics (and 35 years ago, to boot), I wonder if there will be some limit to how far these quantum techniques can be used to factor huge numbers. (Speculation warning!)   A 1 centimeter difference in altitude in Earth's gravitational field results in about a 1 part in 10**18 time dilation.  Even if the atoms making up a quantum computer could be maintained  within 1 micron altitude, that would be a time dilation difference of 1 part in 10**22.   Could there be an effect which would allow the factorization of numbers up to, say, 22 digits long, but that would fail if the number was 301 digits long?  (equivalent to 1024 bits.)   Such a computer might be raised into earth orbit to take advantage of micro-gravity effects, but even that might only raise the limit by a few orders of magnitude, say 22+6 = 28.  Someone much more familiar with quantum mechanics should be able to shed light on this speculation.
         Jim Bell