Xue-Feng Wang

collaborators

3 papers

quant-ph2017

Ranks of quantum states with prescribed reduced states

Chi-Kwong Li, Yiu-Tung Poon

Let $M_{n}$ be the set of $n \times n$ complex matrices. In this note we determine all the possible ranks of a bipartite state in $M_{m} \otimes M_{n}$ with prescribed reduced states in th…

quant-ph2014

Ranks and eigenvalues of states with prescribed reduced states

Chi-Kwong Li, Yiu-Tung Poon, Xuefeng Wang

For a quantum state represented as an $n \times n$ density matrix $σ \in M_{n}$ , let $S (σ)$ be the compact convex set of quantum states $ρ = (ρ_{ij}) \in M_{m \cdot n}$ with the f…

math.SP2014

Perturbing eigenvalues of non-negative matrices

Chi-Kwong Li, Yiu-Tung Poon, Xuefeng Wang

Let $A$ be an irreducible (entrywise) nonnegative $n \times n$ matrix with eigenvalues $ρ, b + i c, b - i c, λ_{4}, \dots, λ_{n},$ where $ρ$ is the Perron eigenvalue. It is shown that for any…