The Chance of Error in Atomic Sized Computers

The first thing that you would worry about when things get very small is Brownian motion--everything is shaking about and nothing stays in place. How can you control the circuits then? Furthermore, if a circuit does work, doesn't it now have a chance of accidentally jumping back? If we use two volts for the energy of this electric system, which is what we ordinarily use, that is eighty times the thermal energy at room temperature (kT=1/40 volt) and the chance that something jumps backward aga...

 A Reversible NAND Gate

The great discovery of Bennett and, independently, of Fredkin is that it is possible to do computation with a different kind of fundamental gate unit, namely, a reversible gate unit. I have illustrated their idea--with a unit which I could call a reversible NAND gate. It has thre inputs and thre outputs. Of the outputs, tow, A' and B', are the same as two of the inputs, A and B, but the third input works this way. C' is the same as C unless A and B are both 1, in which case it changes whateve...

 Dimensions of an Atomic Size Computer

If we somehow manage to make an atomic size computer, it would mean that the dimension, the linear dimension, is a thousand to ten thousand times smaller than those very tiny chips that we have now. It means that the volume of the computer is 100 billionth or 10^-11 of the present volume, because the volume of the "transistor" is smaller by a factor of 10^-11 than the transistors we make today. The energy requirements for a single switch is also about eleven orders of magnitude smaller than t...