From: Lee Corbin (lcorbin@tsoft.com)
Date: Wed Apr 09 2003 - 01:58:23 MDT
Serafino writes
> On Friday, April 04, 2003 10:16 AM
> Lee wrote:
> > So, I'll just go back to my former claim: if you believe physics
> > with all your heart, and so don't suppose that the particular atoms
> > that you are composed of have anything to do with who you are, then
> > you won't mind teleporting, because the pattern of atoms will be
> > the same after as before.
>
> The point, imo, is 'fidelity'.
...
> Now it can be shown... that, due to the no-cloning
> theorem, we can get a *local* quantum transfer or a
> *remote* quantum teleportation of one quantum
> state, with a fidelity f > 2/3, just if we destroy
> the original. It can be shown, also, that without
> destroying the original, we can realize a *local*
> quantum cloning, or a *remote* quantum faxing,
> of several copies (from 2 to n), but in the
> fidelity range of 1/2 < f < 2/3.
>
> Thus, due to the linearity of quantum algebra,
> and due to Heisenberg's relations, it seems very
> difficult to reach, locally or remotely, by deterministic
> or even by probabilistic means, a perfect xoxing,
Yes, but IMO the point is that perfect fidelity is
completely unnecessary. Let us, fancifully, suppose
that the Atmosphere within the room where I am typing
this is to be considered an Operator that operates on
my physical body by bombarding it with many, many more
than 10^20 atomic strikes per second. Suppose that
at the end of 1 microsecond, it transforms me from
|Lee> to O|Lee>, namely into a person not exactly the
same as I was before this microsecond bombardment.
(By the same token, I undergo vast changes internally
that we might suppose to be unaffected, as a first
approximation, by outside influences, and so metaphorically
at least is its own unitary transformation.)
The result is that within one microsecond I am transformed
into a completely different quantum state. Yet I retain
my identity, and I do not consider such operations as
identity-threatening. Now quantum mechanics does allow
in principle that my state might be copied to some remote
location, but with an even smaller similar loss of fidelity.
So long as the loss in fidelity is less than I would experience
in a microsecond anyway, teleportation would create what
is for all practical purposes a physical duplicate, rife
with the philosophical consequences of interest.
Lee
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