| Abstract: | Quantum measurement processes of discrete andcontinuous observables are considered from theinformation-theoretic point of view. The informationextracted from the results of quantum measurementperformed on a physical system and the change of theShannon entropy of the measured physical system areinvestigated in detail. It is shown that the amount ofinformation about the intrinsic observable of themeasured physical system can be expressed by the mutualinformation between the physical system and themeasurement apparatus if the intrinsic observablecommutes with the operational observable defined by thequantum measurement process. Furthermore, the conditioncan be obtained under which the amount of informationextracted from the measurement outcomes becomes equal tothe decrease of the entropy of the measured physical system. In addition, the change of theShannon entropy is compared with that of the von Neumannentropy. The general results do not depend on whetherthe readout of the measurement outcome obeys the projection postulate or not. Severalexamples of quantum measurement processes are consideredto examine the general results. |
