arXiv:1009.5809 · Pacific Journal of Mathematics
A completely positive map associated with a positive map
Erling Størmer
Abstract
STØRMERWe show that each positive map from B(K ) to B(H) is a scalar multiple of a map of the form Trψ with ψ completely positive.This is used to give necessary and sufficient conditions for maps to be Ꮿ-positive for a large class of mapping cones; in particular, we apply the results to k-positive maps.P(B(K ), Ꮿ) = {a ∈ B(K ⊗ H ) : ι ⊗ α(a) ≥ 0 for all α ∈ Ꮿ}, MSC2010: 46L60, 46L99.