Appears in collection : Operator Algebras and Quantum Information Theory

In a unital C*-algebra A possessing a faithful trace, the density operators in A are those positive elements of unit trace, and the set of all density elements forms a convex metric space with respect to the Bures metric. A linear map on A is a channel if it maps density operators to density operators. In this lecture, which is based on joint work with Samuel Jaques and Mizanur Rahaman, I will discuss the structure and properties of channels that are, respectively, isometric and contractive maps of the density space.