On 8/21/2018 3:37 PM, Jason Resch wrote:
On Tue, Aug 21, 2018 at 5:00 PM Brent Meeker <meeke...@verizon.net
<mailto:meeke...@verizon.net>> wrote:
On 8/21/2018 2:40 PM, agrayson2...@gmail.com
<mailto:agrayson2...@gmail.com> wrote:
If I start a 200 qubit quantum computer at time = 0, and 100
microseconds later it has produced a result that required
going through 2^200 = 1.6 x 10^60 = states (more states than
is possible for 200 things to go through in 100 microseconds
even if they changed their state every Plank time (5.39121 x
10^-44 seconds), then physically speaking it **must** have
been simultaneous. I don't see any other way to explain this
result. How can 200 things explore 10^60 states in 10^-4
seconds, when a Plank time is 5.39 x 10^-44 seconds?
It's no more impressive numerically than an electron wave function
picking out one of 10^30 silver halide molecules on a photographic
plate to interact with (which is also non-local, aka simultaneous).
Well consider the 1000 qubit quantum computer. This is a 1 followed by
301 zeros.
What is "this". It's the number possible phase relations between the
1000 qubits. If we send a 1000 electrons toward our photographic plate
through a 1000 holes the Schrodinger wave function approaching the
photographic plate then also has 1e301 different phase relations. The
difference is only that we don't control them so as to cancel out "wrong
answers".
This is not only over a googol^2 times the number of silver halide
molecules in your plate, but more than a googol times the 10^80 atoms
in the observable universe.
What is it, in your mind, that is able to track and consistently
compute over these 10^301 states, in this system composed of only 1000
atoms?
Also note that you can only read off 200bits of information (c.f.
Holevo's theorem).
True, but that is irrelevant to the number of intermediate states
necessary for the computation that is performed to arrive at the final
and correct answer.
But you have to put in 2^200 complex numbers to initiate your qubits.
So you're putting in a lot more information than you're getting out.
Those "intermediate states" are just interference patterns in the
computer, not some inter-dimensional information flow. Also, many
quantum algorithms only give you an answer that is probably correct. So
you have to run it multiple times to have confidence in the result.
Quantum computers will certainly impact cryptography where there's heavy
reliance on factoring primes and discrete logarithms. They should be
able to solve protein folding and similar problems that are out of reach
of classical computers. But they're not a magic bullet. Most problems
will still be solved faster by conventional von Neumann computers or by
specialized neural nets. One reason is that even though a quantum
algorithm is faster in the limit of large problem size, it may still be
slower for the problem size of interest. It's the same problem that
shows up in classical algorithms; for example the Coppersmith-Winograd
algorithm for matrix multiplication takes O(n^2.375) compared to the
Strassen O(n^2.807) but it is never used because it is only faster for
matrices too large to be processed in existing computers.
Brent
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