Y. Poon

activity

20032026

most citedThe automorphism group of separable states in quantum information theory

51 citations · 394 across the 42 of their papers we have counts for

collaborators

Showing 2007Show all

2 papers · 1 filter

math.FA2007★ 34 cited

Higher rank numerical ranges and low rank perturbations of quantum channels

Chi-Kwong Li, Yiu-Tung Poon, Nung-Sing Sze

For a positive integer $k$ , the rank- $k$ numerical range $Λ_{k} (A)$ of an operator $A$ acting on a Hilbert space $\cH$ of dimension at least $k$ is the set of scalars $λ$ such that $…

math.FA2007★ 38 cited

Condition for the higher rank numerical range to be non-empty

Chi-Kwong Li, Yiu-Tung Poon, Nung-Sing Sze

It is shown that the rank- $k$ numerical range of every $n$ -by- $n$ complex matrix is non-empty if $n \geq 3 k - 2$ . The proof is based on a recent characterization of the rank- $k$ num…