caa a22 4500 467906122 CHVBK 20180406152834.0 cr unu---uuuuu 170328e20060701xx s 000 0 eng 10.1007/s10701-006-9053-0 doi (NATIONALLICENCE)springer-10.1007/s10701-006-9053-0 Myers John Division of Engineering and Applied Sciences, Harvard University, 02138, Cambridge, MA, USA aut Conditional Probabilities and Density Operators in Quantum Modeling [Elektronische Daten] [John Myers] Motivated by a recent proof of free choices in linking equations to the experiments they describe, I clarify some relations among purely mathematical entities featured in quantum mechanics (probabilities, density operators, partial traces, and operator-valued measures), thereby allowing applications of these entities to the modeling of a wider variety of physical situations. I relate conditional probabilities associated with projection-valued measures to conditional density operators identical, in some cases but not in others, to the usual reduced density operators. While a fatal obstacle precludes associating conditional density operators with general non-projective measures, tensor products of general positive operator-valued measures (POVMs) are associated with conditional density operators. This association together with the free choice of probe particles allows a postulate of state reductions to be replaced by a theorem. An application shows an equivalence between one form of quantum key distribution and another with respect to certain eavesdropping attacks. Springer Science+Business Media, Inc., 2006 conditional probabilities nationallicence density operators nationallicence POVMs nationallicence tensor products nationallicence partial traces nationallicence quantum cryptography nationallicence Foundations of Physics Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 36/7(2006-07-01), 1012-1035 0015-9018 36:7<1012 2006 36 10701 https://doi.org/10.1007/s10701-006-9053-0 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10701-006-9053-0 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Myers John Division of Engineering and Applied Sciences, Harvard University, 02138, Cambridge, MA, USA aut NATIONALLICENCE 773 0- Foundations of Physics Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 36/7(2006-07-01), 1012-1035 0015-9018 36:7<1012 2006 36 10701 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer