Atomic Computers?

Atoms are busy collections of electrons and nuclear particles that are ever changing their positions in a random dance. In contrast, information storage requires stable states over reasonable time intervals. Can information be stored on individual atoms in their restless world?

Answer

Yes. One can use electron spin directions as binary holders, for example. Even the nuclear spins can join in the game. Quantum computers already use nuclear spins for storage. On a bigger scale, DNA molecules are being used for a DNA computer.

Several difficulties in making atomic computers exist, but all of the difficulties can be overcome by clever techniques. Putting information in and reading information out of these atomic systems have been done in the laboratory already. Maintaining their fixed states is a different kind of problem that depends on which type of system is being used. Nuclear spin systems have been used quite successfully since the 1940s with the development of nuclear magnetic resonance (NMR). Electron spin systems also are controlled quite nicely in labs. If isolation of the system is required, then vacuum chambers work well for long enough time periods of particle isolation.

At the other extreme are proposed quantum computers utilizing the caffeine molecules in a cup of java. They are being bombarded constantly by the other molecules in the liquid, so the liquid environment brings about a rapid decoherence of the system. However, there are an awful lot of caffeine molecules in the cup, at least 10²⁰. The quantum computer requires probably only a million or so to retain their isolation for the duration of the computation time microseconds, perhaps so the numbers may win out.

Like the limits to integrated circuit component density caused by thermal effects and by cosmic ray bombardment, atomic computers also may face similar limits. The type of atomic computer devised will determine how hostile the environment can be.