On 5/7/2019 3:55 PM, Jason Resch wrote:
On Tue, May 7, 2019 at 5:44 PM 'Brent Meeker' via Everything List
<everything-list@googlegroups.com
<mailto:everything-list@googlegroups.com>> wrote:
On 5/7/2019 2:52 PM, Jason Resch wrote:
On Tuesday, May 7, 2019, 'Brent Meeker' via Everything List
<everything-list@googlegroups.com
<mailto:everything-list@googlegroups.com>> wrote:
On 5/7/2019 2:08 PM, Jason Resch wrote:
On Tuesday, May 7, 2019, 'Brent Meeker' via Everything List
<everything-list@googlegroups.com
<mailto:everything-list@googlegroups.com>> wrote:
On 5/7/2019 1:49 PM, Jason Resch wrote:
On Tuesday, May 7, 2019, 'Brent Meeker' via Everything
List <everything-list@googlegroups.com
<mailto:everything-list@googlegroups.com>> wrote:
On 5/7/2019 11:52 AM, Jason Resch wrote:
On Tue, May 7, 2019 at 1:07 PM 'Brent Meeker' via
Everything List <everything-list@googlegroups.com
<mailto:everything-list@googlegroups.com>> wrote:
On 5/7/2019 9:53 AM, Jason Resch wrote:
On Tuesday, May 7, 2019, 'Brent Meeker' via
Everything List
<everything-list@googlegroups.com
<mailto:everything-list@googlegroups.com>> wrote:
On 5/6/2019 11:11 PM, Jason Resch wrote:
Not at all. In fact a quantum
computation only works because all
the wrong answers have a high
probability of being eliminated by
destructive interference...which
requires that they be computed in
the same world.
So prior to the computation, all of the
wrong answers existed?
There is no answer until the output is
measured.
Brent
Then what did you mean by "all the wrong
answers have a high probability of being
eliminated". Eliminated from what?
I mean not showing up as the answer.
And they don't show up because... ?
Their amplitude in the superposition is small. If
you've got something to say, just say it.
Brent
You seem to be avoiding the implication that the system
starts in a state where all possible answers, both
wrong and correct exist.
You seem to think that because something might exist in
the future it exists.
Brent
At what point in time does "the probability of measuring the
wrong answers" decrease?
1. Before the computation
2. During/after the computation
3. At the time of measurement
4. Something else
5. Indeterminate
My guess is #2, what do you think?
During/after is pretty broad. You're assuming that when the
answer is measured can be varied independently of the
computation. Even classical computations don't have an
answer ready to be output at any time. Some do, but interate
so that the answer becomes more accurate with run time. So I
think it depends on the structure of the algorithm.
Brent
Is there an algorithm where the answer would be something other
than during or after?
Since the question was ''At what /*point*/ in time does "the
probability of measuring the wrong answers" decrease?'' I don't
thing "during/after" is even an answer.
As I said, I think no answer exists until there's a measurement,
the computer will be in a superposition of states relative to the
measurement basis. So "at the time of measurement" would be the
closest answer. But I know some algorithms, like Grover's, become
more accurate as they run longer.
Isn't there an easy experiment to test your theory? Run the following
experiment: Execute the same quantum computation simultaneously on 5
different quantum computers. Then:
1. On computer #1, perform the measurement 1 year after the
computation completes
2. On computer #2, perform the measurement 2 hours after the
computation completes
3. On computer #3, perform the measurement 1 hour after the
computation completes
4. On computer #4, perform the measurement as soon as the computation
completes
5. On computer #5, perform the measurement before the computation
completes
Given that QM would give us the same probability of obtaining the
correct answer from computers 1 through 4, and a different (lower)
probability of obtaining the correct answer from computer #5, and
given that the measurements take place at different times (with the
earliest taking place as soon as the computation completes), doesn't
this suggest to you that the probabilities are determined prior to the
time of the measurement?
Of course in a sense the probabilities are determined when the problem,
including the measurement, is defined (at least insofar as we trust the
theory of QM). But for at least some algorithms the answer is more
likely to be correct if we let the computation run longer. But that
only suggests that at any given iteration of those algorithms the
probability of a measurement result is becoming more concentrated on the
right answer. For algorithms like Grover's "the computation completes"
corresponds to a measurement being made, there is no other sense of
"computation completes". I don't know if that's true of all quantum
algorithms.
Brent
--
You received this message because you are subscribed to the Google Groups
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
To view this discussion on the web visit
https://groups.google.com/d/msgid/everything-list/715921b2-afcb-08de-f3d5-3417cdbddd7c%40verizon.net.
For more options, visit https://groups.google.com/d/optout.
