On 10/06/2017 2:36 am, Telmo Menezes wrote:
On Fri, Jun 9, 2017 at 12:37 AM, Bruce Kellett
The idea that the explanation is epistemological rather that ontological has
been my preferred position for a long time. If the wave-function is merely
an epistemological device for calculating probabilities and not a really
existing object, all worries about collapse and action-at-a-distance vanish.
Of course, multi worlds also vanish, but in my opinion that is no bad thing.
So what's your position on Deutsch's argument about quantum computers?
Where does the extra computing power come from?
It has long been understood that Deutsch is out to lunch on this. He
appears to assume that a quantum computer is just using the same
algorithms that a classical computer would use, only executing them in a
massively parallel manner. This is manifestly false. Quantum computers
operate in a completely different way -- that is why there are so few
actual algorithms for quantum computers to execute that gain massive
speed improvements.
As Brent says in his recent post, Scott Aaronson points out:
"The way a quantum algorithms work is that they arrange for wrong
answers to destructively interfere while the desired answer interferes
constructively. Interference requires that they take place in the same
world."
Classical computers do not have quantum interference. Quantum computing
does not prove the existence of parallel worlds -- there is no need for
other worlds in which to find the computational power, you just need a
modicum of insight into how quantum computing algorithms work.
You might claim that Deutsch is a known expert on quantum computing, but
more commonly, Deutsch is known for having way out, non-standard ideas
on quantum mechanics.
Bruce
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