From observables and states to Hilbert space and back: a 2-categorical adjunction
Abstract
Given a representation of a C*-algebra, thought of as an abstract collection of physical observables, together with a unit vector, one obtains a state on the algebra via restriction. We show that the Gelfand-Naimark-Segal (GNS) construction furnishes a left adjoint of this restriction. To properly formulate this adjoint, it must be viewed as a weak natural transformation, a 1-morphism in a suitable 2-category, rather than as a functor between categories. Weak naturality encodes the functoriality and the universal property of adjunctions encodes the characterizing features of the GNS construction. Mathematical definitions and results are accompanied by physical interpretations.
Keywords
Cite
@article{arxiv.1609.08975,
title = {From observables and states to Hilbert space and back: a 2-categorical adjunction},
author = {Arthur J. Parzygnat},
journal= {arXiv preprint arXiv:1609.08975},
year = {2018}
}
Comments
30 pages + appendix; post-peer-review, pre-copyedit version of an article published in Applied Categorical Structures