Computing in Parallel Universes
When One Universe Just Isn't Enough > Page 1,
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Actually building a quantum computer is hard. Really hard. You
might recall I said before
that you are not allowed to look at the intermediate states of a
quantum computer or you destroy the calculation. In the world of
quantum measurements, not looking is tricky. Just letting your
quantum computer interact with the environment is equivalent to
looking in many cases. That means everything needs to be properly
isolated and secure, yet we need to be able to make the computer do
what it needs to do and we need to be able to interact with it to
program it. This fine balance is difficult to achieve and there have
been many proposals for how to go about it.
The first attempts have been made using single ions trapped by
electromagnetic fields. Unfortunately, the ions jiggle around in the
traps and that introduces errors. Also, you need to do everything in
a vacuum and with some pretty sophisticated laser technology. Not
the sort of thing that is likely to end up on people's desks.
However, the experiments showed the successful operation of a
one-bit quantum computer. OK, so that's very useful but it did show
that quantum computing is possible in principle.
A very promising scheme is being developed in Australia by Bruce
Kane of the University of New South Wales and co-workers. It uses
silicon technologies and uses the nuclear spins within atoms to
store the quantum information and act as the quantum computer. The
great thing about that proposal is that it can be controlled using
conventional silicon technology and be scaled up to many bits. The
researchers are building at this very moment.
The latest concrete result comes from the IBM
labs where a five bit quantum computer has been constructed.
Their computer consists of five fluorine atoms in a molecule such
that the spins of the fluorine nuclei an interact with each other as
the bits. The bits are controlled by radiofrequency pulses and
detected by nuclear magnetic resonance images just like those used
in hospitals for MRI scans.
There is a lot more to say about quantum computing but we'll
leave it here for this week. Keep an eye out in the future more
articles about the various details of quantum computers - or maybe
those articles already exist in some superposition with this one.
It's just a shame that you looked because you're stuck with this one
for now. I'll just have to set up the experiment again and design it
for a different article to pop out at you...
To find out more about quantum computing, check out the following
Physics site pages:
Links
to Quantum Computing information
Links
to Quantum Physics information
and then pop on over to the Nanotechnology site to see
More
links to Quantum Computing
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