Maps Preserving Schatten p-Norms of Convex Combinations

We study maps ϕ of positive operators of the Schatten p-classes (1<p<+∞), which preserve the p-norms of convex combinations, that is,   ∥tρ+(1-t)σ∥p=∥tϕ(ρ)+(1-t)ϕ(σ)∥p,  ∀ρ,σ∈𝒮p+(H)1,  t∈[0,1]. They are exactly those carrying the form ϕ(ρ)=UρU* for a unitary or antiunitary U. In the case p=...

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Main Authors: David Li-Wei Kuo, Ming-Cheng Tsai, Ngai-Ching Wong, Jun Zhang
Format: Article
Language:English
Published: Wiley 2014-01-01
Series:Abstract and Applied Analysis
Online Access:http://dx.doi.org/10.1155/2014/520795
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author David Li-Wei Kuo
Ming-Cheng Tsai
Ngai-Ching Wong
Jun Zhang
author_facet David Li-Wei Kuo
Ming-Cheng Tsai
Ngai-Ching Wong
Jun Zhang
author_sort David Li-Wei Kuo
collection DOAJ
description We study maps ϕ of positive operators of the Schatten p-classes (1<p<+∞), which preserve the p-norms of convex combinations, that is,   ∥tρ+(1-t)σ∥p=∥tϕ(ρ)+(1-t)ϕ(σ)∥p,  ∀ρ,σ∈𝒮p+(H)1,  t∈[0,1]. They are exactly those carrying the form ϕ(ρ)=UρU* for a unitary or antiunitary U. In the case p=2, we have the same conclusion whenever it just holds ∥ρ+σ∥2=∥ϕ(ρ)+ϕ(σ)∥2 for all the positive Hilbert-Schmidt class operators ρ,σ of norm 1. Some examples are demonstrated.
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institution Kabale University
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language English
publishDate 2014-01-01
publisher Wiley
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series Abstract and Applied Analysis
spelling doaj-art-b292eb66fe4f46ce887713bfdd8796602025-08-20T03:39:21ZengWileyAbstract and Applied Analysis1085-33751687-04092014-01-01201410.1155/2014/520795520795Maps Preserving Schatten p-Norms of Convex CombinationsDavid Li-Wei Kuo0Ming-Cheng Tsai1Ngai-Ching Wong2Jun Zhang3Department of Applied Mathematics, National Sun Yat-Sen University, Kaohsiung 80424, TaiwanDepartment of Applied Mathematics, National Sun Yat-Sen University, Kaohsiung 80424, TaiwanDepartment of Applied Mathematics, National Sun Yat-Sen University, Kaohsiung 80424, TaiwanSchool of Mathematics and Statistics, Central China Normal University, Wuhan, Hubei 430079, ChinaWe study maps ϕ of positive operators of the Schatten p-classes (1<p<+∞), which preserve the p-norms of convex combinations, that is,   ∥tρ+(1-t)σ∥p=∥tϕ(ρ)+(1-t)ϕ(σ)∥p,  ∀ρ,σ∈𝒮p+(H)1,  t∈[0,1]. They are exactly those carrying the form ϕ(ρ)=UρU* for a unitary or antiunitary U. In the case p=2, we have the same conclusion whenever it just holds ∥ρ+σ∥2=∥ϕ(ρ)+ϕ(σ)∥2 for all the positive Hilbert-Schmidt class operators ρ,σ of norm 1. Some examples are demonstrated.http://dx.doi.org/10.1155/2014/520795
spellingShingle David Li-Wei Kuo
Ming-Cheng Tsai
Ngai-Ching Wong
Jun Zhang
Maps Preserving Schatten p-Norms of Convex Combinations
Abstract and Applied Analysis
title Maps Preserving Schatten p-Norms of Convex Combinations
title_full Maps Preserving Schatten p-Norms of Convex Combinations
title_fullStr Maps Preserving Schatten p-Norms of Convex Combinations
title_full_unstemmed Maps Preserving Schatten p-Norms of Convex Combinations
title_short Maps Preserving Schatten p-Norms of Convex Combinations
title_sort maps preserving schatten p norms of convex combinations
url http://dx.doi.org/10.1155/2014/520795
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AT ngaichingwong mapspreservingschattenpnormsofconvexcombinations
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