Quantum mechanics and the activities of subatomic particles play a significant role in the design and operation of processors. When those processors are scaled down in size and bumped up in speed, as IBM has done with the Power6, the actions of those forces and particles become a significant factor in chip design.
One good example is something that IBM calls “leakage.” Leakage is the tendency of the electrons in the conductors within a processor to leak out. Physicist Werner Heisenberg described the property of quantum-level objects such that it was impossible to know both the momentum and the position of an object. Since you know the momentum of an electron inside a processor (because you know its mass and the speed of light in that context), you cant also know where it is, exactly. Thus the leakage problem.
IBM engineers have managed to minimize leakage through conductor design and the design of insulating material, but they have not eliminated it.
Something they had even less success in eliminating was the interaction of subatomic particles. At this level, even something wed never notice, such as a cosmic ray, can disrupt the operations of a processor. The reasons for this are the small scale (65 nanometers) and the low voltage at which the Power6 operates.
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Cosmic rays are really high-energy particles, mostly protons, that pass into the earths atmosphere from space. When they strike something—say, a conductor or other component inside a processor—they can change its state, and that can result in a change in how an instruction is processed.
This in turn causes an error. IBM engineers cant prevent these high-energy particles, and they cant really shield against them. This is made worse because the particles are everywhere.
To alleviate the problem, IBMs scientists and engineers chose to institute error correction to keep these particles from interrupting operations. The Power6 is massively instrumented, and it checks itself for errors at every clock cycle. When it finds a soft error, it reruns the instruction, and that in turn fixes errors caused by high-energy particles.
But one thing IBM hasnt talked about is another principle of quantum mechanics: that the act of observation changes the outcome of quantum events. Presumably, this would also include both leakage and high-energy particle interactions. With the Power6 constantly observing itself, what then?
Physicist Erwin Schrödinger once proposed a thought experiment in which a test subject—he suggested a cat—would be placed in a sealed container, and its life or death determined by the random decay of a single particle. Until the cat was observed, he suggested, the cat existed in both states, both alive and dead. Then, the act of observation alone would cause one of those states to exist.
Perhaps by creating a processor that also observes itself, IBM has managed to find a handle on the world of quantum mechanics in addition to its speed and its abilities with floating point calculations.
Technical Analyst Wayne Rash can be reached at [email protected]
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