Physical limitations of rate, depth, and minimum energy in information processing

Abstract

The effect of the quantum nature of matter on the maximum informationprocesssing potentialities is considered. It is shown that the degeneracy of the energy levels of a physical information-processing system results in the fact that a universal limit of information-processing rates does not exist, though for any specific system this rate is indeed bounded. A physical interpretation is then proposed for an elementary act of information-processing and the concept of information-processing depth is introduced. The example of a system of quantum oscillators is used to show that the maximal information-processing depth is bounded, only a very small fraction of the possible system states being used. The effect of thermal noise on information processing is briefly discussed.