Can Schrodinger's Cat Factor Numbers?
Suppose we wish to factor a 500-bit number N (assumed to be a product
of 2 large primes). We construct a hard-wired division circuit that
outputs the remainder R of N when divided by an input D. We know that
if N is composite then it has a divisor of 250 bits or less, so our
circuit only needs to handle 250-bit inputs.
If we flip a fair coin 250 times and use the results to set the input
bits, then the probability of finding a factor is roughly 1/(2^250).
This is just equivalent to randomly guessing a number between 1 and
sqrt(N). Not very efficient.
But suppose we perform 250 "Schrodinger's Cat" experiments in a giant
sealed room, and connect the results to the inputs of our division
circuit (which is also contained in the sealed room). Now instead of
a 1/(2^250) chance that the remainder is zero, quantum theory tells
us that the remainder (from our perspective outside the sealed room)
is the linear superposition of all 2^250 possible outcomes, one of
which is R=0.
I suppose as soon as we observe the result, it takes on just one of the
2^250 possible outcomes, and the probability of the outcome R=0 is just
1/(2^250), so nothing has been gained.
But the idea that, in the unobserved room, the R=0 condition is
actually THERE seems very tantalizing. Is it conceivable that some
sort of feedback amplification could be used to enhance the R=0
outcome? We know that seemingly mutually exclusive outcomes of quantum
processes can actually interfere with each other, as in the "two-slit
experiments". Could we similarly detect interference effects of the
R=0 outcome on the other possible outcomes?
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