An abstract characterization for projections in operator systems
arXiv:2006.03094
Abstract
We show that the set of projections in an operator system can be detected using only the abstract data of the operator system. Specifically, we show that if is a positive contraction in an operator system which satisfies certain order-theoretic conditions, then there exists a complete order embedding of into mapping to a projection operator. Moreover, every abstract projection in an operator system is an honest projection in the C*-envelope of . Using this characterization, we provide an abstract characterization for operator systems spanned by two commuting families of projection-valued measures and discuss applications in quantum information theory.
Final version. To appear in Journal of Operator Theory