84 citations · 379 across the 37 of their papers we have counts for
6 papers · 1 filter
Recursive encoding and decoding of the noiseless subsystem for qudits
Utkan Güngördü, Chi-Kwong Li, Mikio Nakahara +2
We give a full explanation of the noiseless subsystem that protects a single-qubit against collective errors and the corresponding recursive scheme described by C.-K. Li et. al. [P…
Conditions for degradability of tripartite quantum states
Chi-Hang Fred Fung, Chi-Kwong Li, Nung-Sing Sze +1
Alice, Bob, and Eve share a pure quantum state. We introduce the notion of state degradability by asking whether the joint density of Alice and Eve can be transformed to the joint…
Determinantal and eigenvalue inequalities for matrices with numerical ranges in a sector
Chi-Kwong Li, Nung-Sing Sze
Let $A = \pmatrix A_{11} & A_{12} \cr A_{21} & A_{22}\cr\pmatrix \in M_n$, where with , be such that the numerical range of lies in the set $\{e^{iφ…
Maximal noiseless code rates for collective rotation channels on qudits
Chi-Kwong Li, Mikio Nakahara, Yiu-Tung Poon +1
We study noiseless subsystems on collective rotation channels of qudits, i.e., quantum channels with operators in the set ${\mathcal E}(d,n) = \{ U^{\otimes n}: U \in {\mathrm{SU}}…
Factorization of permutations
Zejun Huang, Chi-Kwong Li, Sharon H. Li +1
We consider the problem of factoring permutations as a product of special types of transpositions, namely, those transpositions involving two positions with bounded distances. In p…
Linear maps preserving the higher numerical ranges of tensor product of matrices
Ajda Fošner, Zejun Huang, Chi-Kwong Li +2
We study linear maps preserving the higher numerical ranges of tensor product of matrices.