[cryptography] How far are we from quantum cryptography?

David Johnston dj at deadhat.com
Mon Jan 26 01:20:30 EST 2015

On 1/25/15, 9:34 PM, Watson Ladd wrote:
> No, D-wave didn't make a quantum computer capable of running Shor's 
> algorithm. It's unclear if D-wave's device even works, and there are 
> certain theoretical reasons to suspect it didn't. See 
> http://www.scottaaronson.com/blog/?p=1400 for actual people who know 
> things saying things.
I have this suspicion that since you have to make your qbits colder to 
get more of them to remain entangled, and cooling one part of space 
requires that you warm some other, under the laws of thermodynamics, 
then maybe it can be shown the the energy needed to spend to get those 
qbits cold enough to run Shor's algorithm over n bits is equal to or 
greater than the energy necessary to perform the equivalent operations 
in serial in a normal computer. This would be a useful finding in 
information theory and cryptography if it was true.

Sadly I lack the mathematical skills to show or refute this.

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