Re: Quantum Computing

From: Tommy McCabe (
Date: Mon Jul 26 2004 - 09:08:12 MDT

--- Aaron McBride <> wrote:
> Tommy McCabe wrote:
> > <clip>
> >
> >Spin, in quantum particles, refers to, basically,
> how
> >many revolutions a particle goes through before it
> >looks identical to when it started. Particles can
> have
> >whole-numbered spins, like 1, or decimal spins,
> like
> >1/2. Thus, we can classify particles based on their
> >native spin. And though there are an infinite
> number
> >of different spins, such a statement about the
> >capacity of these electrons would require there to
> be
> >a total of ~2*2^(10^27) different spins used. This
> >strikes me as being huge enough to be highly
> unlikely.
> >Mind you, I am not a physicist either, so if anyone
> >has a more accurate explanation of what spin is or
> how
> >it can be used to store information, please don't
> >hesitate to correct me.
> >
> >
> >
> I'm no physicist either, but I don't think you're
> quite right when you
> say there are an infinite number of spins. All
> electrons are spin 1/2.
> All photons are spin 1. Etc...
> I believe (and this is where I don't really
> understand what I'm talking
> about) anytime you measure the spin of an electron
> it either comes out
> as "up" or "down", never part way in between. So,
> there are really two
> states for the spin of an electron. (Yaaay, binary
> rules!)
> Because they are fuzzy little things, and you don't
> know if they're up
> or down until you measure them, they're really
> distributed between the
> two states. One hundred electrons like this would
> then, in a way be in
> 2^100 different states at once. Somehow with
> quantum computers, this is
> useful. I think when they're talking about lots of
> hard drives, they're
> trying to compare that 2^100 with how many hard
> drives it would take to
> list all of the numbers between 0 and 2^100-1
> simultaneously.

If quantum superpositions collapse when we try to
observe them, how do we know they exist in the first
place? According to Heinsberg's uncertainty principle,
you can't know the exact speed or location of a
particle, but what does that have to do with spin? And
the double-slit experiment definetly produces some odd
results, but again, what does that have to do with a
particles' spin?

> Ok, that's enough conjecture from me. Are there any
> real physicists or
> quantum computer scientists in the house that can
> clear this up?
> -Aaron

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