2010/02/28 by Runyao Duan, Simone Severini, Andreas Winter · 7 citations
Computer Science · Mathematics · Physics and Astronomy · #Classical capacity #Generalization #Hilbert space #Operator (biology) #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum capacity #Quantum channel #Quantum information #Quantum operation #Tensor product #cs.IT #math.IT #math.OA #quant-ph
paper · pdf · doi:10.1109/tit.2012.2221677
published as IEEE Trans. Inf. Theory 59(2):1164-1174, 2013 · 24 pages: v2 has added discussion and more details in section 7.
arxiv created 2010/03/11 · openalex publication_date 2012/10/02 · arxiv updated 2013/04/19 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We study the quantum channel version of Shannon's zero-error capacity problem. Motivated by recent progress on this question, we propose to consider a certain subspace of operators (so-called operator systems) as the quantum generalization of the adjacency matrix, in terms of which the zero-error capacity of a quantum channel, as well as the quantum and entanglement-assisted zero-error capacities can be formulated, and for which we show some new basic properties. Most importantly, we define a quantum version of Lovász' famous ϑ function on general operator systems, as the norm-completion (or stabilization) of a “naive” generalization of ϑ. We go on to show that this function upper bounds the number of entanglement-assisted zero-error messages, that it is given by a semidefinite program, whose dual we write down explicitly, and that it is multiplicative with respect to the tensor product of operator systems (corresponding to the tensor product of channels). We explore various other properties of the new quantity, which reduces to Lovász' original ϑ in the classical case, give several applications, and propose to study the operator systems associated with channels as “noncommutative graphs,” using the language of Hilbert modules.