5,130 research outputs found
Time evolution techniques for detectors in relativistic quantum information
The techniques employed to solve the interaction of a detector and a quantum
field typically require perturbation methods. We introduce mathematical
techniques to solve the time evolution of an arbitrary number of detectors
interacting with a quantum field. Our techniques apply to harmonic oscillator
detectors and can be generalized to treat detectors modeled by quantum fields.
Since the interaction Hamiltonian we introduce is quadratic in creation and
annihilation operators, we are able to draw from continuous variable techniques
commonly employed in quantum optics.Comment: 13 pages, 1 figure, updated to published version . I. Fuentes
previously published as I. Fuentes-Guridi and I. Fuentes-Schulle
A discrete Schrodinger spectral problem and associated evolution equations
A recently proposed discrete version of the Schrodinger spectral problem is
considered. The whole hierarchy of differential-difference nonlinear evolution
equations associated to this spectral problem is derived. It is shown that a
discrete version of the KdV, sine-Gordon and Liouville equations are included
and that the so called `inverse' class in the hierarchy is local. The whole
class of related Darboux and Backlund transformations is also exhibited.Comment: 14 pages, LaTeX2
Additional Recursion Relations, Factorizations, and Diophantine Properties Associated with the Polynomials of the Askey Scheme
In this paper, we apply to (almost) all the "named" polynomials of the Askey scheme, as defined by their standard three-term recursion relations, the machinery developed in previous papers. For each of these polynomials we identify at least one additional recursion relation involving a shift in some of the parameters they feature, and for several of these polynomials characterized by special values of their parameters, factorizations are identified yielding some or all of their zeros—generally given by simple expressions in terms ofintegers(Diophantinerelations). The factorization findings generally are applicable for values of the Askey polynomials that extend beyond those for which the standard orthogonality relations hold. Most of these results are not (yet) reported in the standard compilations
engineering thoughts on hydrogen embrittlement
Abstract Hydrogen Embrittlement (HE) is a topical issue for pipelines transporting sour products. Engineers need a simple and effective approach in materials selection at design stage. In other words, they must know if a material is susceptible to cracking, to be able of: selecting the right material and apply correct operational measures during the service life. Following ASTM F2078, HE is "a permanent loss of ductility in a metal or alloy caused by hydrogen in combination with stress, either externally applied or internal residual stress". In many cases, hydrogen can play a role in crack propagation, as for instance in Stress Corrosion Cracking (SCC) and Corrosion Fatigue (CF). Three parameters are required to cause failure: presence of hydrogen, tensile stress, and material susceptibility. The two previous ones are triggering the failure, while the root cause is usually material susceptibility. This is why material selection is the important step to safely manage engineering structural materials. As an example, material selection for sour service pipeline is the object of well-known standards, e.g. by Nace International and EFC: they pose some limits in the sour service of steels, with reference to surface hardness. These standards have shown some weak points, namely: In the definition of sour service; In defining the role of crack initiation and propagation, considering that in Hydrogen embrittlement, stress state and stress variations are very important. As for the second point, in hydrogen generation anodic processes shall be taken into account too. For instance, there is a relationship between corrosion resistance and crack susceptibility. In carbon and low alloy steels, cracking will not normally occur when there is a significant corrosion rate. If a brittle layer (or a brittle spot) is present on the metal surface, this one can initiate a crack
Localised projective measurement of a relativistic quantum field in non-inertial frames
We propose a scheme to study the effect of motion on measurements of a
quantum field carried out by a finite-size detector. We introduce a model of
projective detection of a localised field mode in an arbitrary reference frame.
We apply it to extract vacuum entanglement by a pair of counter-accelerating
detectors and to estimate the Unruh temperature of a single accelerated
detector. The introduced method allows us to directly relate the observed
effects with the instantaneous proper acceleration of the detector.Comment: 5 pages, 2 figures. v2 Significant increase in the detail level
regarding the motivation of the detector mode
The “Eyeballing” technique : an emerging and alerting trend of alcohol misuse
Alternative methods of alcohol consumption have recently emerged among adolescents and young adults, including the alcohol “eyeballing”, which consist in the direct pouring of alcoholic substances on the ocular surface epithelium. In a context of drug and behavioural addictions change, “eyeballing” can be seen as one of the latest and potentially highly risky new trends. We aimed to analyze the existing medical literature as well as online material on this emerging trend of alcohol misusePeer reviewedFinal Published versio
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