Quantum Measured Information

Abstract

A framework for a quantum information theory is introduced that is based on the measure of quantum information associated with probability distribution predicted by quantum measuring of state. The entanglement between states of measured system and "pointer" states of measuring apparatus, which is generated by dynamical process of quantum measurement, plays a dominant role in expressing quantum characteristics of information theory. The quantum mutual information of transmission and reception of quantum states along a noisy quantum channel is given by the change of quantum measured information. In our approach, it is not necessary to purify the transmitted state by means of the reference system. It is also clarified that there exist relations between the approach given in this letter and those given by other authors.