31 citations · 111 across the 13 of their papers we have counts for
9 papers · 1 filter
Realizations of free actions via their fixed point algebras
Kay Schwieger, Stefan Wagner
Let be a compact group, let be a unital C-algebra, and let be a free C-dynamical system, in the sense of Ellwood, with fixed point alg…
An Atiyah Sequence for Noncommutative Principal Bundles
Kay Schwieger, Stefan Wagner
We present a derivation-based Atiyah sequence for noncommutative principal bundles. Along the way we treat the problem of deciding when a given -automorphism on the quantum bas…
Lifting spectral triples to noncommutative principal bundles
Kay Schwieger, Stefan Wagner
Given a free action of a compact Lie group on a unital C*-algebra and a spectral triple on the corresponding fixed point algebra , we present a sys…
Noncommutative Coverings of Quantum Tori
Kay Schwieger, Stefan Wagner
We introduce a framework for coverings of noncommutative spaces. Moreover, we study noncommutative coverings of irrational quantum tori and characterize all such coverings that are…
Part III, Free Actions of Compact Quantum Groups on C*-Algebras
Kay Schwieger, Stefan Wagner
We study and classify free actions of compact quantum groups on unital C*-algebras in terms of generalized factor systems. Moreover, we use these factor systems to show that all fi…
Part II, Free Actions of Compact Groups on C*-Algebras
Kay Schwieger, Stefan Wagner
We study a simple subclass of free actions of non-Abelian groups on unital C*-algebras, namely cleft actions. These are characterized by the fact that the associated noncommutative…
Part I, Free Actions of Compact Abelian Groups on C*-Algebras
Kay Schwieger, Stefan Wagner
We study free and compact group actions on unital C*-algebras. In particular, we provide a complete classification theory of these actions for compact Abelian groups and explain it…
Diagonal Couplings of Quantum Markov Chains
Burkhard Kümmerer, Kay Schwieger
In this article we extend the coupling method from classical probability theory to quantum Markov chains on atomic von Neumann algebras. In particular, we establish a coupling ineq…
Ergodic Properties of Quantum Birth and Death Chains
David Bücher, Andreas Gärtner, Burkhard Kümmerer +3
We study a class of quantum Markov processes that, on the one hand, is inspired by the micromaser experiment in quantum optics and, on the other hand, by classical birth and death…