On 09/08/2013 06:54 PM, Leo Gaspard wrote: > Well... If factoring takes a month, with the factor of 125, it takes > ten years. Seems not that irrelevant to me.
Or you wait three years and let technological progression reduce the work factor for you. Or you throw 125 machines at it instead of one. Or... etc. If something is unsafe at work level X, it won't be safe at work level 125X. > Strangely enough, I would have thought 4k qubits would be quite a > huge need, thus meaning we would have overcome the major problems > with decoherence. There's a big difference between physics and engineering. For an example, look at the history of aviation. During the era of propeller-driven aircraft we were limited by the engineering constraints of piston-driven propellers. People said, "ah, but if we could only perfect jet propulsion we could accelerate as fast as we wanted!" Well-respected engineers like Buckminster Fuller talked about doing space launches with jet aircraft -- accelerating up to orbital velocity, releasing the satellite, and landing the delivery aircraft again. Once we invented jet engines we discovered those were pipe dreams. There was a new limitation that no one had considered prior to the perfection of jet engines: since the air in the engine must be slowed to subsonic velocities, that sharply limits just how far supersonic a jet engine can go. There was a new speed limit to replace the old speed limit -- and a speed limit we didn't foresee until we actually had the new technology to play with. Nowadays people are talking about developing scramjets to overcome the limitations of jet engines -- supersonic combustion within the engine. And the old ideas from the 1920s are coming back around again, of using scramjets to deliver satellites (or bombs, if you're working on defense contracts). And I have no doubt that if/when we perfect scramjet technology we'll discover a new limitation, one we couldn't have foreseen before we had working scramjets to play with. So, yeah. A 4k ensemble would mean we'd overcome the decoherence problem, but really, so would a 200-qubit ensemble, or even a 50-bit ensemble. I'm not skeptical about our ability to overcome decoherence; Bill Unruh tells me that we know how to do it in a physics level and it's only a matter of time until engineering catches up. I'm skeptical about our ability to overcome the new limits which will arise, limits we are at present unaware of. > But, again, not being a quantum physicist, I cannot be relied upon > on that subject. Nor am I, but Bill Unruh is. :) I also attended grad school with Ben Moehlmann, who has since received his Ph.D. in quantum computation. Ben's been a great resource over the years for this stuff. I never have a conversation with him without walking away staggering under the weight of the new knowledge. I am not a quantum computation expert, but I hang out with some really cool nerds. :) _______________________________________________ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
