Gianfranco
Created page with "===3.4. General theory (Davies–Lewis–Ozawa)=== Finally, we formulate the general notion of quantum instrument. A superoperator acting in <math display="inline">\mathcal{L}(\mathcal{H})</math> is called positive if it maps the set of positive semi-definite operators into itself. We remark that, for each '''<u><math>x,\Im_A(x)</math></u>''' given by (13) can be considered as linear positive map. Generally any map<math>x\rightarrow\Im_A(x)</math> , where for each <m..."