2,055 research outputs found
Advanced control with a Cooper-pair box: stimulated Raman adiabatic passage and Fock-state generation in a nanomechanical resonator
The rapid experimental progress in the field of superconducting nanocircuits
gives rise to an increasing quest for advanced quantum-control techniques for
these macroscopically coherent systems. Here we demonstrate theoretically that
stimulated Raman adiabatic passage (STIRAP) should be possible with the
quantronium setup of a Cooper-pair box. The scheme appears to be robust against
decoherence and should be realizable even with the existing technology. As an
application we present a method to generate single-phonon states of a
nanomechnical resonator by vacuum-stimulated adiabatic passage with the
superconducting nanocircuit coupled to the resonator
Entanglement monotones and maximally entangled states in multipartite qubit systems
We present a method to construct entanglement measures for pure states of
multipartite qubit systems. The key element of our approach is an antilinear
operator that we call {\em comb} in reference to the {\em hairy-ball theorem}.
For qubits (or spin 1/2) the combs are automatically invariant under
SL(2,\CC). This implies that the {\em filters} obtained from the combs are
entanglement monotones by construction. We give alternative formulae for the
concurrence and the 3-tangle as expectation values of certain antilinear
operators. As an application we discuss inequivalent types of genuine four-,
five- and six-qubit entanglement.Comment: 7 pages, revtex4. Talk presented at the Workshop on "Quantum
entanglement in physical and information sciences", SNS Pisa, December 14-18,
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Histologic, Immunohistochemical and Morphometric Study of the Mucosa of the total gastric antrum in Patients with carcinoma of the stomach.
Comparative Studies of Low-Intensity Short-Length Arcs
We present results obtained by two non-equilibrium modelling approaches and experiments on low-intensity short-length arcs in argon at atmospheric pressure. The first one considers a quasi-neutral arc column combined with boundary conditions on the electrodes based on the energy balance in the space-charge sheaths. The second approach applies a unified description over the entire gap and solves the Poisson equation for the self-consistent electric field. The experiments provide the arc voltage
Coherent tunneling by adiabatic passage in an optical waveguide system
We report on the first experimental demonstration of light transfer in an
engineered triple-well optical waveguide structure which provides a classic
analogue of Coherent Tunnelling by Adiabatic Passage (CTAP) recently proposed
for coherent transport in space of neutral atoms or electrons among
tunneling-coupled optical traps or quantum wells [A.D. Greentree et al., Phys.
Rev. B 70, 235317 (2004); K. Eckert et al., Phys. Rev. A 70, 023606 (2004)].
The direct visualization of CTAP wavepacket dynamics enabled by our simple
optical system clearly shows that in the counterintuitive passage scheme light
waves tunnel between the two outer wells without appreciable excitation of the
middle well.Comment: submitted for publicatio
On the formation of the welding seams with high speed
Целью настоящей работы является определение направлений исследований по установлению возможности повышения качества формирования сварочных швов с повышенной скоростью формирования тела шва. В статье вопрос решается путём отклонения сварочной дуги углом вперед, поперечным магнитным полем. Дополнительное магнитное поле в зоне сварки генерируют, пропуская часть сварочного тока по присадочной проволоке. Проволока подается в сварочную ванну позади дуги параллельно электроду в плоскости свариваемого стыка, в направлении, противоположном току дуги. Проведенный анализ отечественных и зарубежных литературных источников по рассматриваемой теме показал, что современный подход к определению влияния на повышение качества формирования сварочных швов с повышенной скоростью формирования тела шва, за счет дополнительного поперечного магнитного поля является актуальным в настоящее время и недостаточно изучен. Приведены сведения о формировании тела шва при скоростной сварке вольфрамовым электродом с присадочной проволокой, которые могут быть использованы для повышения производительности сварочных работ.The aim of this work is to determine the areas of research to establish the possibility of improving the quality of the formation of welds with an increased rate of formation of the joint body. In the article the problem is solved by the deviation of the arc angle forward transverse magnetic field. Additional magnetic field generated in the welding zone by passing part of the welding current for the filler wire. The wire is fed into the weld puddle behind the arc electrode in the plane parallel to the welded joint, in a direction opposite to the arc current. The analysis of domestic and foreign literature on the topic has shown that the modern approach to determine the effect on the improvement of quality of formation of welds with an increased rate of formation of the joint body, due to the additional transverse magnetic field is relevant in the present and not fully understood. Information is given about the formation of a seam in the tungsten electrode welding with filler wire, which can be used to improve the performance of welding
The Wright ω Function
This paper defines the Wright ω function, and presents some of its properties. As well as being of intrinsic mathematical interest, the function has a specific interest in the context of symbolic computation and automatic reasoning with nonstandard functions. In particular, although Wright ω is a cognate of the Lambert W function, it presents a di#erent model for handling the branches and multiple values that make the properties of W difficult to work with. By choosing a form for the function that has fewer discontinuities (and numerical difficulties), we make reasoning about expressions containing such functions easier. A final point of interest is that some of the techniques used to establish the mathematical properties can themselves potentially be automated, as was discussed in a paper presented at AISC Madrid [3]
Preparation and characterization of X ray mirrors with three single layers of a C, B4C and Ni onto two 820 mm long Si substrate
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