quantum computing and the brain

From: Miriam English (miriam@werple.net.au)
Date: Sun Oct 07 2001 - 19:14:08 MDT

Maybe some of you can help with flabbergastering thoughts...

I don't understand how a quantum computer can work, but I read a little
time back that it can do multiple calculations simulataneously. That is, if
you have 2 qubits they can perform 4 calculations at once by simultaneously
experiencing (in some way I can't begin to understand) all possible state
combinations at once. Similarly that 3 qubits "feel out" 8 states, 4 qubits
16 states, and so on.

This would be a pretty impressive computer if I have that right. Would that
make it possible to handle all the computations of all the neurons (10^12)
and synapses (perhaps 10^3 per neuron) of the brain even taking into
account about 1,000 levels of exciteability for each synapse... with just
60 qubits!!?

That can't be right... can it?

It must require at least one qubit to store an item of information, even if
calculations can be made in different ways simultaneously on that one bit
of info, it is still just one bit.

Even if each bit can be a single atom (one day in the future) that still
makes a tiny human mind -- using 10^18 atoms for storage. The entire mind
would not be that small of course because you still need some way to
shuttle the info around inside it, but even if the the means of moving data
around required 100,000 atoms for each storage atom the entire thing is
still just a sixth of a mole of material! If the "brain" used
nanostructures of pure carbon for instance then that would be a device
weighing just 2 grams (Avogadro's constant puts 6*10^23 atoms of carbon at
12 grams).

Anybody know if either of these back-of-the-envelope scenarios approaches
good sense?


         - Miriam

To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.
Virtual Reality Association http://www.vr.org.au

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