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Quantum states satisfying classical probability constraints

Elena R. Loubenets (2006)

Banach Center Publications

For linear combinations of quantum product averages in an arbitrary bipartite state, we derive new quantum Bell-form and CHSH-form inequalities with the right-hand sides expressed in terms of a bipartite state. This allows us to specify bipartite state properties sufficient for the validity of a classical CHSH-form inequality and the perfect correlation form of the original Bell inequality for any bounded quantum observables. We also introduce a new general condition on a bipartite state and quantum...

Quantum stochastic processes arising from the strong resolvent limits of the Schrödinger evolution in Fock space

Alexander Chebotarev, Dmitry Victorov (1998)

Banach Center Publications

By using F. A. Berezin's canonical transformation method [5], we derive a nonadapted quantum stochastic differential equation (QSDE) as an equation for the strong limit of the family of unitary groups satisfying the Schrödinger equation with singularly degenerating Hamiltonians in Fock space. Stochastic differentials of QSDE generate a nonadapted associative Ito multiplication table, and the coefficients of these differentials satisfy the formal unitarity conditions of the Hudson-Parthasarathy type...

Quasi *-algebras and generalized inductive limits of C*-algebras

Giorgia Bellomonte, Camillo Trapani (2011)

Studia Mathematica

A generalized procedure for the construction of the inductive limit of a family of C*-algebras is proposed. The outcome is no more a C*-algebra but, under certain assumptions, a locally convex quasi *-algebra, named a C*-inductive quasi *-algebra. The properties of positive functionals and representations of C*-inductive quasi *-algebras are investigated, in close connection with the corresponding properties of positive functionals and representations of the C*-algebras that generate the structure....

Quasi *-algebras of measurable operators

Fabio Bagarello, Camillo Trapani, Salvatore Triolo (2006)

Studia Mathematica

Non-commutative L p -spaces are shown to constitute examples of a class of Banach quasi *-algebras called CQ*-algebras. For p ≥ 2 they are also proved to possess a sufficient family of bounded positive sesquilinear forms with certain invariance properties. CQ*-algebras of measurable operators over a finite von Neumann algebra are also constructed and it is proven that any abstract CQ*-algebra (,₀) with a sufficient family of bounded positive tracial sesquilinear forms can be represented as a CQ*-algebra...

Quasiaffine transforms of operators

Il Bong Jung, Eungil Ko, Carl Pearcy (2009)

Studia Mathematica

We obtain a new sufficient condition (which may be useful elsewhere) that a compact perturbation of a normal operator be the quasiaffine transform of some normal operator. We also give some applications of this result.

Quasicompact endomorphisms of commutative semiprime Banach algebras

Joel F. Feinstein, Herbert Kamowitz (2010)

Banach Center Publications

This paper is a continuation of our study of compact, power compact, Riesz, and quasicompact endomorphisms of commutative Banach algebras. Previously it has been shown that if B is a unital commutative semisimple Banach algebra with connected character space, and T is a unital endomorphism of B, then T is quasicompact if and only if the operators Tⁿ converge in operator norm to a rank-one unital endomorphism of B. In this note the discussion is extended in two ways: we discuss endomorphisms of commutative...

Quasiconformal mappings and exponentially integrable functions

Fernando Farroni, Raffaella Giova (2011)

Studia Mathematica

We prove that a K-quasiconformal mapping f:ℝ² → ℝ² which maps the unit disk onto itself preserves the space EXP() of exponentially integrable functions over , in the sense that u ∈ EXP() if and only if u f - 1 E X P ( ) . Moreover, if f is assumed to be conformal outside the unit disk and principal, we provide the estimate 1 / ( 1 + K l o g K ) ( | | u f - 1 | | E X P ( ) ) / ( | | u | | E X P ( ) ) 1 + K l o g K for every u ∈ EXP(). Similarly, we consider the distance from L in EXP and we prove that if f: Ω → Ω’ is a K-quasiconformal mapping and G ⊂ ⊂ Ω, then 1 / K ( d i s t E X P ( f ( G ) ) ( u f - 1 , L ( f ( G ) ) ) ) / ( d i s t E X P ( f ( G ) ) ( u , L ( G ) ) ) K for every u ∈ EXP(). We also prove that...

Quasi-constricted linear operators on Banach spaces

Eduard Yu. Emel'yanov, Manfred P. H. Wolff (2001)

Studia Mathematica

Let X be a Banach space over ℂ. The bounded linear operator T on X is called quasi-constricted if the subspace X : = x X : l i m n | | T x | | = 0 is closed and has finite codimension. We show that a power bounded linear operator T ∈ L(X) is quasi-constricted iff it has an attractor A with Hausdorff measure of noncompactness χ | | · | | ( A ) < 1 for some equivalent norm ||·||₁ on X. Moreover, we characterize the essential spectral radius of an arbitrary bounded operator T by quasi-constrictedness of scalar multiples of T. Finally, we prove that every...

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