1202.5905 (Juha-Pekka Pellonpää)

Completely positive maps on modules, instruments, extremality problems,
and applications to physics    [PDF]

Juha-Pekka Pellonpää

Convex sets of completely positive maps and positive semidefinite kernels are considered in the most general context of modules over $C^*$-algebras and a complete charaterization of their extreme points is obtained. As a byproduct, we determine extreme quantum instruments, preparations, channels, and extreme autocorrelation functions. Various applications to quantum information and measurement theories are given. The structure of quantum instruments is analyzed thoroughly.

View original: http://arxiv.org/abs/1202.5905