(英) |
We give a talk on an attempt to establish a systematic treatment of measurement correlations in quantum theory. We define the concept of system of measurement correlations, which is the exact counterpart of instrument in the (generalized) Heisenberg picture. We then define the concept of measuring process, which is consistent with the definition of system of measurement correlations. In quantum mechanical systems, we establish a one-to-one correspondence between systems of measurement correlations and measuring processes up to complete equivalence. This is nothing but a unitary dilation theorem of systems of measurement correlations. Next, from the viewpoint of the statistical approach to quantum measurement theory, we focus on the extendability of CP instruments to systems of measurement correlations. It is shown that all CP instruments are extended into systems of measurement correlations. Moreover, in the case of injective von Neumann algebras, we show that any CP instruments are approximated by faithful measuring processes within arbitrarily given error limits. |