All a b c d e f g h i j k l m n o p q r s t u v w x y z Other

Previous Page 3 Next

Displaying 41 – 60 of 204

Showing per page

Comparing quantum dynamical entropies

P. Tuyls (1998)

Banach Center Publications

Last years, the search for a good theory of quantum dynamical entropy has been very much intensified. This is not only due to its usefulness in quantum probability but mainly because it is a very promising tool for the theory of quantum chaos. Nowadays, there are several constructions which try to fulfill this need, some of which are more mathematically inspired such as CNT (Connes, Narnhofer, Thirring), and the one proposed by Voiculescu, others are more inspired by physics such as ALF (Alicki,...

Control on weak asymptotic abelianness with the help of the crossed product construction

Heide Narnhofer (1998)

Banach Center Publications

The crossed product construction is used to control in some examples the asymptotic behaviour of time evolution. How invariant states on a small algebra can be extended to invariant states on a larger algebra reduces to solving an eigenvalue problem. In some cases (the irrational rotation algebra) this eigenvalue problem has only trivial solutions and by reduction of the subalgebra control on all invariant states can be found.

Covariance algebra of a partial dynamical system

Bartosz Kosma Kwaśniewski (2005)

Open Mathematics

A pair (X, α) is a partial dynamical system if X is a compact topological space and α: Δ→ X is a continuous mapping such that Δ is open. Additionally we assume here that Δ is closed and α(Δ) is open. Such systems arise naturally while dealing with commutative C *-dynamical systems. In this paper we construct and investigate a universal C *-algebra C *(X,α) which agrees with the partial crossed product [10] in the case α is injective, and with the crossed product by a monomorphism [22] in the case...

Crossed products by Hilbert pro-C*-bimodules

Maria Joiţa, Ioannis Zarakas (2013)

Studia Mathematica

We define the crossed product of a pro-C*-algebra A by a Hilbert A-A pro-C*-bimodule and we show that it can be realized as an inverse limit of crossed products of C*-algebras by Hilbert C*-bimodules. We also prove that under some conditions the crossed products of two Hilbert pro-C*-bimodules over strongly Morita equivalent pro-C*-algebras are strongly Morita equivalent.

Decompositions of Beurling type for E₀-semigroups

Rolf Gohm (2006)

Banach Center Publications

We define tensor product decompositions of E₀-semigroups with a structure analogous to a classical theorem of Beurling. Such decompositions can be characterized by adaptedness and exactness of unitary cocycles. For CCR-flows we show that such cocycles are convergent.

Dynamical entropy of a non-commutative version of the phase doubling

Johan Andries, Mieke De Cock (1998)

Banach Center Publications

A quantum dynamical system, mimicking the classical phase doubling map z ↦ z 2 on the unit circle, is formulated and its ergodic properties are studied. We prove that the quantum dynamical entropy equals the classical value log2 by using compact perturbations of the identity as operational partitions of unity.

Currently displaying 41 – 60 of 204