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Quantum Information Theory of Entanglement and Measurement
We present a quantum information theory that allows for a consistent
description of entanglement. It parallels classical (Shannon) information
theory but is based entirely on density matrices (rather than probability
distributions) for the description of quantum ensembles. We find that quantum
conditional entropies can be negative for entangled systems, which leads to a
violation of well-known bounds in Shannon information theory. Such a unified
information-theoretic description of classical correlation and quantum
entanglement clarifies the link between them: the latter can be viewed as
``super-correlation'' which can induce classical correlation when considering a
tripartite or larger system. Furthermore, negative entropy and the associated
clarification of entanglement paves the way to a natural information-theoretic
description of the measurement process. This model, while unitary and causal,
implies the well-known probabilistic results of conventional quantum mechanics.
It also results in a simple interpretation of the Kholevo theorem limiting the
accessible information in a quantum measurement.Comment: 26 pages with 6 figures. Expanded version of PhysComp'96 contributio
Logical Entropy: Introduction to Classical and Quantum Logical Information theory
Logical information theory is the quantitative version of the logic of partitions just as logical probability theory is the quantitative version of the dual Boolean logic of subsets. The resulting notion of information is about distinctions, differences and distinguishability and is formalized using the distinctions of a partition. All the definitions of simple, joint, conditional and mutual entropy of Shannon information theory are derived by a uniform transformation from the corresponding definitions at the logical level. The purpose of this paper is to give the direct generalization to quantum logical information theory that similarly focuses on the pairs of eigenstates distinguished by an observable, i.e., qudits of an observable. The fundamental theorem for quantum logical entropy and measurement establishes a direct quantitative connection between the increase in quantum logical entropy due to a projective measurement and the eigenstates that are distinguished by the measurement. Both the classical and quantum versions of logical entropy have simple interpretations as “two-draw” probabilities for distinctions. The conclusion is that quantum logical entropy is the simple and natural notion of information for quantum information theory focusing on the distinguishing of quantum states
Acquisition of Information is Achieved by the Measurement Process in Classical and Quantum Physics
No consensus seems to exist as to what constitutes a measurement which is
still considered somewhat mysterious in many respects in quantum mechanics. At
successive stages mathematical theory of measure, metrology and measurement
theory tried to systematize this field but significant questions remain open
about the nature of measurement, about the characterization of the observer,
about the reliability of measurement processes etc. The present paper attempts
to talk about these questions through the information science. We start from
the idea, rather common and intuitive, that the measurement process basically
acquires information. Next we expand this idea through four formal definitions
and infer some corollaries regarding the measurement process from those
definitions. Relativity emerges as the basic property of measurement from the
present logical framework and this rather surprising result collides with the
feeling of physicists who take measurement as a myth. In the closing this paper
shows how the measurement relativity wholly consists with some effects
calculated in QM and in Einstein's theory.Comment: Prepared for : Quantum Theory: Reconsideration of Foundations - 4
(QTFR-4), Vaxjo, Sweden, 6-11 June 2007. To be published by the American
Institute of Physics in the AIP Conference Proceedings series. Talk presented
by Paolo Rocch
Strategic-decision quality in public organizations : an information processing perspective
This study draws on information processing theory to investigate predictors of strategic-decision quality in public organizations. Information processing theory argues that (a) rational planning practices contribute to strategic-decision quality by injecting information into decision-making and (b) decision-makers contribute to strategic-decision quality by exchanging information during decision-making. These assumptions are tested upon fifty-five Flemish pupil guidance centers. Rational planning practices are operationalized as strategic planning, performance measurement and performance management. Information exchange by decision-makers during decision-making is operationalized as procedural justice of the decision-making process. Results suggest that procedural justice, strategic planning and performance management contribute to strategic-decision quality while performance measurement does not
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