60,262 research outputs found
ooRexx 5 Yielding Swiss Army Knife Usability
The new version 5.0 of the message based object-oriented programming language ooRexx ("open object-oriented REXX") is easy to learn, yet powerful. This article introduces some of the new language features with nutshell examples that at the same time demonstrate its power when deployed in different operating system environments. The modern native API of ooRexx makes it in addition very easy to extend the language with new functionality and deploy it as a macro language for any C++-based application
Convex Trace Functions on Quantum Channels and the Additivity Conjecture
We study a natural generalization of the additivity problem in quantum
information theory: given a pair of quantum channels, then what is the set of
convex trace functions that attain their maximum on unentangled inputs, if they
are applied to the corresponding output state?
We prove several results on the structure of the set of those convex
functions that are "additive" in this more general sense. In particular, we
show that all operator convex functions are additive for the Werner-Holevo
channel in 3x3 dimensions, which contains the well-known additivity results for
this channel as special cases.Comment: 9 pages, 1 figure. Published versio
Privacy sets for constrained space-filling
The paper provides typology for space filling into what we call "soft" and
"hard" methods along with introducing the central notion of privacy sets for
dealing with the latter. A heuristic algorithm based on this notion is
presented and we compare its performance on some well-known examples
Casimir energy density in closed hyperbolic universes
The original Casimir effect results from the difference in the vacuum
energies of the electromagnetic field, between that in a region of space with
boundary conditions and that in the same region without boundary conditions. In
this paper we develop the theory of a similar situation, involving a scalar
field in spacetimes with compact spatial sections of negative spatial
curvature.Comment: 10 pages. Contribution to the "Fifth Alexander Friedmann
International Seminar on Gravitation and Cosmology," Joao Pessoa, Brazil,
2002. Revised version, with altered Abstract and one new referenc
On the Incommensurate Phase in Modulated Heisenberg Chains
Using the density matrix renormalization group method (DMRG) we calculate the
magnetization of frustrated S=1/2 Heisenberg chains for various modulation
patterns of the nearest neighbour coupling: commensurate, incommensurate with
sinusoidal modulation and incommensurate with solitonic modulation. We focus on
the order of the phase transition from the commensurate dimerized phase (D) to
the incommensurate phase (I). It is shown that the order of the phase
transition depends sensitively on the model. For the solitonic model in
particular, a -dependent elastic energy modifies the order of the
transition. Furthermore, we calculate gaps in the incommensurate phase in
adiabatic approximation.Comment: 8 pages, 9 figure
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