arXiv subjects
Publications and source records attributed to Kyung Hoon Han.
Based on the Archimedeanization developed by Paulsen and Tomforde, we give an explicit description for the positive cones of maximal tensor products of function systems. From this description, we obtain an approximation theorem for nuclear maps between function systems. As an application, we give elementary proofs on several characterizations of nuclear function systems that are already known.
We consider bi-linear analogues of $s$-positivity for linear maps. The dual objects of these notions can be described in terms of Schimdt ranks for tri-tensor products and Schmidt numbers for tri-partite quantum states. These tri-partite versions of Schmidt numbers cover various kinds of bi-separability, and so we may interpret witnesses for those in terms of bi-linear maps. We give concrete examples of witnesses for various kinds of three qubit entanglement.
For a $C^*$-algebra $\mathcal A$ and a von Neumann algebra $\mathcal R$, we describe the predual of space $D(\mathcal A,\mathcal R)$ of decomposable maps from $\mathcal A$ into $\mathcal R$ equipped with decomposable norm. This predual is found to be the matrix regular operator space structure on $\mathcal A \otimes \mathcal R_*$ with a certain universal property. Its matrix norms are the largest and its positive cones on each matrix level are the smallest among all possible matrix regular operator space structures on $\mathcal A \otimes \mathcal R_*$ under the two natural restrictions: (1) $|x \otimes y| \le |x| |y|$ for $x\in M_k(\mathcal A), y \in M_l(\mathcal R_*)$ and (2) $v \otimes w$ is positive if $v \in M_k(\mathcal A)^+$ and $w \in M_l(\mathcal R_*)^+$.
We introduce quotient maps in the category of operator systems and show that the maximal tensor product is projective with respect to them. Whereas, the maximal tensor product is not injective, which makes the $({\rm el},\max)-nuclearity distinguish a class in the category of operator systems. We generalize Lance's characterization of $C^*$-algebras with the WEP by showing that $({\rm el},\max)$-nuclearity is equivalent to the weak expectation property. Applying Werner's unitization to the dual spaces of operator systems, we consider a class of completely positive maps associated with the maximal tensor product and establish the duality between quotient maps and complete order embeddings.
We prove that an operator system $\mathcal S$ is nuclear in the category of operator systems if and only if there exist nets of unital completely positive maps $ϕ_λ: \cl S \to M_{n_λ}$ and $ψ_λ: M_{n_λ} \to \cl S$ such that $ψ_λ\circ ϕ_λ$ converges to ${\rm id}_{\cl S}$ in the point-norm topology. Our proof is independent of the Choi-Effros-Kirchberg characterization of nuclear $C^*$-algebras and yields this characterization as a corollary. We give an example of a nuclear operator system that is not completely order isomorphic to a unital $C^*$-algebra.
We establish a relationship between Schreiner's matrix regular operator space and Werner's (nonunital) operator system. For a matrix ordered operator space $V$ with complete norm, we show that $V$ is completely isomorphic and complete order isomorphic to a matrix regular operator space if and only if both $V$ and its dual space $V^*$ are (nonunital) operator systems.
We show that noncommutative $L_p$-spaces satisfy the axioms of the (nonunital) operator system with a dominating constant $2^{1 \over p}$. Therefore, noncommutative $L_p$-spaces can be embedded into $B(H)$ $2^{1 \over p}$-completely isomorphically and complete order isomorphically.