Nice error bases have been introduced by Knill (1996) as a generalization of the Pauli basis.
These bases are shown to be projective representations of finite groups. We classify all nice …

This title deals with a map $\alpha $ from a finite group $ G $ into the automorphism group $
Aut ({\mathcal L}) $ of a factor ${\mathcal L} $ satisfying (i) $ G= N\rtimes H $ is a semi-direct …

Maximal connected grading classes of a finite-dimensional algebra $ A $ are in one-to-one
correspondence with Galois covering classes of $ A $ which admit no proper Galois …

Let k be an algebraically closed field of characteristic p. We give a general method for
producing examples of blocks B of finite group algebras that are not Morita equivalent as k …

We show that for any compact connected group G the second cohomology group defined by
unitary invariant two-cocycles on Ĝ is canonically isomorphic to. This implies that the group …

Quotient grading classes are essential participants in the computation of the intrinsic
fundamental group π 1 (A) of an algebra A. In order to study quotient gradings of a finite …

Nice error bases have been introduced by Knill as a generalization of the Pauli basis. These
bases are shown to be projective representations of finite groups. We classify all nice error …

In this article we study relations between groups and quantum error correcting codes.
Groups of central type are used to construct quantum error correcting codes. Both stabilizer …

We show that for any compact connected group G the second cohomology group de ned by
unitary invariant 2-cocycles on^ G is canonically isomorphic to H2 (\Z (G); T). This implies …

Algebraic methods play an important role in coding theory. For instance, there are many
connections between codes and groups. In this paper we will present two results that show …