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2-category 2-category-theory abelian-categories adjoint algebra algebraic algebraic-geometry algebraic-topology analysis analytic-geometry arithmetic arithmetic-geometry book bundles calculus categorical categories category category-theory chern-weil-theory cohesion cohesive-homotopy-type-theory cohomology colimits combinatorics complex complex-geometry computable-mathematics computer-science constructive cosmology deformation-theory descent diagrams differential differential-cohomology differential-equations differential-geometry digraphs duality elliptic-cohomology enriched fibration finite foundation foundations functional-analysis functor gauge-theory gebra geometric-quantization geometry graph graphs gravity grothendieck group group-theory harmonic-analysis higher higher-algebra higher-category-theory higher-differential-geometry higher-geometry higher-lie-theory higher-topos-theory homological homological-algebra homotopy homotopy-theory homotopy-type-theory index-theory integration integration-theory k-theory lie-theory limits linear linear-algebra locale localization logic mathematics measure-theory modal modal-logic model model-category-theory monad monads monoidal monoidal-category-theory morphism motives motivic-cohomology nlab noncommutative noncommutative-geometry number-theory of operads operator operator-algebra order-theory pages pasting philosophy physics pro-object probability probability-theory quantization quantum quantum-field quantum-field-theory quantum-mechanics quantum-physics quantum-theory question representation representation-theory riemannian-geometry scheme schemes set set-theory sheaf sheaves simplicial space spin-geometry stable-homotopy-theory stack string string-theory superalgebra supergeometry svg symplectic-geometry synthetic-differential-geometry terminology theory topology topos topos-theory tqft type type-theory universal variational-calculus

1. • CommentRowNumber1.
   • CommentAuthorUrs
   • CommentTimeSep 18th 2023
   • (edited Sep 18th 2023)
   • PermaLink
   Author: Urs
   Format: MarkdownItexdiscovered this old entry. The page history shows that it wasn't touched since its creation in March 2010 (as a somewhat ill-formatted stub) until an anonymous editor added a substantial paragraph in May this year (2023). The old entry had raised the open question of determining the stability of extremality of channels under tensor product, and this was just recently addressed in * James Miller, S. T. da Silva, *On the Extremality of the Tensor Product of Quantum Channels* &lbrack;[arXiv;2305.05795](https://arxiv.org/abs/2305.05795)&rbrack; I guess the added paragraph (and possibly its author) is from this preprint. In any case, I have tried to polish up this entry a little, fixing the worst formatting glitches. But it remains a stub. <a href="https://ncatlab.org/nlab/revision/diff/extremal+quantum+channel/5">diff</a>, <a href="https://ncatlab.org/nlab/revision/extremal+quantum+channel/5">v5</a>, <a href="https://ncatlab.org/nlab/show/extremal+quantum+channel">current</a>

   discovered this old entry.

   The page history shows that it wasn’t touched since its creation in March 2010 (as a somewhat ill-formatted stub) until an anonymous editor added a substantial paragraph in May this year (2023).

   The old entry had raised the open question of determining the stability of extremality of channels under tensor product, and this was just recently addressed in

   • James Miller, S. T. da Silva, On the Extremality of the Tensor Product of Quantum Channels [arXiv;2305.05795]

   I guess the added paragraph (and possibly its author) is from this preprint.

   In any case, I have tried to polish up this entry a little, fixing the worst formatting glitches. But it remains a stub.

   diff, v5, current