Chi-Kwong Li

activity

19962025

most citedCanonical forms, higher rank numerical range, convexity, totally isotropic subspace, matrix equations

84 citations · 657 across the 85 of their papers we have counts for

collaborators

Showing 2014Show all

10 papers · 1 filter

math.FA2014

Preservers of Unitary Similarity Functions on Lie Products of Matrices

Jianlian Cui, Chi-Kwong Li, Yiu-Tung Poon

Denote by $M_{n}$ the set of $n \times n$ complex matrices. Let $f : M_{n} \to [0, \infty)$ be a continuous map such that $f (μU A U^{*}) = f (A)$ for any complex unit $μ$ , $A \in M_{n}$ a…

math.FA2014

Spectral radius, numerical radius, and the product of operators

Rahim Alizadeh, Mohammad B. Asadi, Che-Man Cheng +2

Let $σ (A)$ , $ρ (A)$ and $r (A)$ denote the spectrum, spectral radius and numerical radius of a bounded linear operator $A$ on a Hilbert space $H$ , respectively. We show that a linear…

math.RA2014★ 2 cited

Positivity of Partitioned Hermitian Matrices with Unitarily Invariant Norms

Chi-Kwong Li, Fuzhen Zhang

We give a short proof of a recent result of Drury on the positivity of a $3 \times 3$ matrix of the form $(∥ R_{i}^{*} R_{j} ∥_{tr})_{1 \leq i, j \leq 3}$ for any rectangular complex (or…

math.NA2014

Projection methods in quantum information science

Yuen-Lam Cheung, Dmitriy Drusvyatskiy, Chi-Kwong Li +2

We consider the problem of constructing quantum operations or channels, if they exist, that transform a given set of quantum states ${ρ_{1}, \dots, ρ_{k}}$ to another such set $\{\ha…

quant-ph2014★ 20 cited

Discontinuity of Maximum Entropy Inference and Quantum Phase Transitions

Jianxin Chen, Zhengfeng Ji, Chi-Kwong Li +5

In this paper, we discuss the connection between two genuinely quantum phenomena --- the discontinuity of quantum maximum entropy inference and quantum phase transitions at zero te…

math.FA2014

Factoring a quadratic operator as a product of two positive contractions

Chi-Kwong Li, Ming-Cheng Tsai

Let $T$ be a quadratic operator on a complex Hilbert space $H$ . We show that $T$ can be written as a product of two positive contractions if and only if $T$ is of the form $$aI \op…