1,084 research outputs found
Physical interpretation of the Wigner rotations and its implications for relativistic quantum information
We present a new treatment for the spin of a massive relativistic particle in
the context of quantum information based on a physical interpretation of the
Wigner rotations, obtaining different results in relation to the previous
works. We are lead to the conclusions that it is not possible to define a
reduced density matrix for the particle spin and that the Pauli-Lubanski (or
similar) spin operators are not suitable to describe measurements where spin
couples to an electromagnetic field in the measuring apparatus. These
conclusions contradict the assumptions made by most of the previous papers on
the subject. We also propose an experimental test of our formulation.Comment: 10 pages, 2 figures. Several changes were made on the text. One extra
example was include
Geometrically induced singular behavior of entanglement
We show that the geometry of the set of quantum states plays a crucial role
in the behavior of entanglement in different physical systems. More
specifically it is shown that singular points at the border of the set of
unentangled states appear as singularities in the dynamics of entanglement of
smoothly varying quantum states. We illustrate this result by implementing a
photonic parametric down conversion experiment. Moreover, this effect is
connected to recently discovered singularities in condensed matter models.Comment: v2: 4 pags, 4 figs. A discussion before the proof of Proposition 1
and tomographic results were included, Propostion 2 was removed and the
references were fixe
Solving Large Scale Crew Scheduling Problems in Practice
This paper deals with large-scale crew scheduling problems arising at the Dutch railway operator, Netherlands Railways (NS). NS operates about 30,000 trains a week. All these trains need a driver and a certain number of guards. Some labor rules restrict the duties of a certain crew base over the complete week. Therefore splitting the problem in several subproblems per day leads to suboptimal solutions.
In this paper, we present an algorithm, called LUCIA, which can solve such huge instances without splitting. This algorithm combines Lagrangian heuristics, column generation and fixing techniques. We compare the results with existing practice. The results show that the new method significantly improves the solution
Mapeamento de áreas de preservação permanente de topo de morro na bacia hidrográfica do Alto Camaquã, RS, nos termos da resolução CONAMA de 2002 (revogado) e do Novo Código Florestal de 2012.
Cinza de biomassa florestal como insumo para plantio de Pinus taeda em Cambissolo e Latossolo em Vargem Bonita, SC.
bitstream/item/215476/1/com-tec187.pd
Delimitação da bacia hidrográfica do Camaquã: comparação de métodos automatizados. Delimitation of Camaquã´s hydrographic river basin: evaluation of automated methods.
Alterações químicas no solo e resposta de Pinus taeda L. à aplicação de doses de cinza de biomassa vegetal.
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