2020/05/01 by Robert Furber
Computer Science · Mathematics · #cs.LO #math.OA
paper · pdf · doi:10.4204/eptcs.318.5
published as EPTCS 318, 2020, pp. 66-84 · In Proceedings QPL 2019, arXiv:2004.14750
arxiv created 2020/05/01 · arxiv updated 2020/05/04
Scott continuity is a concept from domain theory that had an unexpected previous life in the theory of von Neumann algebras. Scott-continuous states are known as normal states, and normal states are exactly the states coming from density matrices. Given this, and the usefulness of Scott continuity in domain theory, it is natural to ask whether this carries over to generalized probabilistic theories. We show that the answer is no - there are infinite-dimensional convex sets for which the set of Scott-continuous states on the corresponding set of 2-valued POVMs does not recover the original convex set, but is strictly larger. This shows the necessity of the use of topologies for state-effect duality in the general case, rather than purely order theoretic notions.