Simple quantum systems as a source of coherent information

A set of very important simple quantum systems is analyzed from the standpo int of the amount of coherent information that is accessible when informati on channels corresponding to the systems are used. It is shown that for sim ple quantum models the coherent information can be calculated and used for estimating the potential possibilities of the corresponding quantum channel as a source of physical information in experiments associated with the eff ects of the coherence of quantum states. The following physical models are studied: a two-level atom in a laser radiation field, an aggregate of two t wo-level subsystems in a multilevel atom (hydrogen), a system of two two-le vel atoms in the process of joint quantum-deterministic evolution and under the action of transformations of quantum measurement and quantum duplicati on, as well as one and two two-level atoms in the process of emission. (C) 2000 MAIK "Nauka/ Interperiodica".