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2 votes
0 answers
267 views

Example of a unital contractive map that is not completely positive on an operator system

I am aware of maps that are positive but not completely positive (for example transpose map). BUT I can not think of an example of the following type. Does there exist an operator $T$ such that a map $...
Piku's user avatar
  • 231
3 votes
0 answers
179 views

Stinespring's theorem: can we choose the dilation to be an isometry?

Let $A$ be a $C^*$-algebra and $\varphi: A \to B(H)$ be a completely positive contractive map. Stinespring's theorem says that there exists a $*$-representation $\pi: A \to B(H')$ and a bounded ...
Andromeda's user avatar
  • 175
3 votes
0 answers
181 views

Completely positive, unital maps acting on unitary operators [solved]

Call a completely positive, irreducible, unital map $E$ on the operators on a finite-dimensional Hilbert-space primitive if there is only a single eigenvalue with modulus 1 (all others have modulus &...
Henrik's user avatar
  • 31
1 vote
1 answer
190 views

Bounded operators on the Stinespring representation space

Let $A$ be a $C^*$-algebra and let $\phi:A\to B(H)$ be a completely positive map. The Stinespring representation theorem constructs a representation of $A$ on a Hilbert space $K$, which is constructed ...
user10439561's user avatar