infinity%udel-cc-vax2.delaware@udel-louie.ARPA (07/03/85)
From: ALBERS <infinity%udel-cc-vax2.delaware@udel-louie.ARPA> Given the technology to do it, the smallest a computer memory could be made would probably be an electron, in that a spin in one direction would be a one and a spin in the other direction would be a zero. Don't ask me how you would go about building a computer around this, but give computer technology about 10 years to find a way. Eric
meister@linus.UUCP (Phillip W. Servita) (07/12/85)
> > Given the technology to do it, the smallest a computer memory >could be made would probably be an electron, in that a spin in one >direction would be a one and a spin in the other direction would be a >zero. Don't ask me how you would go about building a computer around >this, but give computer technology about 10 years to find a way. > > Eric there is a problem here. according to Heisenberg, reading a file would irreversibly garble it. -phil
rimey@ucbmiro.ARPA (Ken Rimey) (07/13/85)
>> Given the technology to do it, the smallest a computer memory >>could be made would probably be an electron, in that a spin in one >>direction would be a one and a spin in the other direction would be a >>zero. ... >> Eric > > there is a problem here. according to Heisenberg, reading a file >would irreversibly garble it. > > -phil You say that sensing the spin of an electron would garble it. I don't see why. Is your reference to Heisenberg a reference to the Heisenberg uncertainty principle? I don't see how it applies. It relates to pairs of simultaneously unknowable observables. For example, if you measure the momentum of a particle you disturb its position. This is simply because a state of well-defined momentum is a plane-wave, which clearly does not have a well-defined position. Excuse me if you already know this. Anyway, I don't see that this prevents you from non-destructively measuring whether a spin is up or down. Am I missing something? Ken Rimey
cej@ll1.UUCP (One of the Jones Boys) (07/14/85)
>>Given the technology to do it, the smallest a computer memory >>could be made would probably be an electron, in that a spin in one >>direction would be a one and a spin in the other direction would be a >>zero. ... >> Eric > > there is a problem here. according to Heisenberg, reading a file >would irreversibly garble it. > > -phil That's no problem. Core memory is a destructive-read meory device, also. All that's required is that you write the data back after each read operation. -- disclaimer: I'm the one looking for the control on the T.V. to turn up the intelligence. The one marked brightness doesn't seem to work. ...ihnp4!mgnetp!ll1!cej Llewellyn Jones ----------------------------------------------------------
mcgeer%ucbkim%Berkeley@sri-unix.ARPA (07/17/85)
From: Rick McGeer (on an aaa-60-s) <mcgeer%ucbkim@Berkeley> See Mead & Conway, Chapter 9
BARD@MIT-XX.ARPA (07/21/85)
From: Bard Bloom <BARD@MIT-XX.ARPA>
{ re: a message saying that the smallest possible memory element is a
single electron, using its spin to hold a bit }
> there is a problem here. according to Heisenberg, reading a file
> would irreversibly garble it.
A minor problem. Read it; make a copy of it on some more stable substance,
like a disk or vellum parchment or RAM, copy that copy back to the electrons,
and use the stable copy. The intermediate steps are easy. Reading and writing
electron spins are left as an exercise for the reader
-- Bard --
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