1,172 research outputs found
Derivations of relativistic force transformation equations
The correct general form of relativistic transformation
equations for the three-vector force is derived without using four-vectors, via the relativistic Newton's second law. The four-vector approach to the problem is also presented. The derivations extend or rectify previous derivations
Canonical approach to the closed string noncommutativity
We consider the closed string moving in the weakly curved background and its
totally T-dualized background. Using T-duality transformation laws, we find the
structure of the Poisson brackets in the T-dual space corresponding to the
fundamental Poisson brackets in the original theory. From this structure we
obtain that the commutative original theory is equivalent to the
non-commutative T-dual theory, whose Poisson brackets are proportional to the
background fluxes times winding and momenta numbers. The non-commutative theory
of the present article is more nongeometrical then T-folds and in the case of
three space-time dimensions corresponds to the nongeometric space-time with
-flux.Comment: We add the Sec. 4. where we compared our results with previous ones.
We also improved Abstract, Introduction and Conclusion as described above. In
addition, we corrected all typos and grammatical errors we notice
Description of classical and quantum interference in view of the concept of flow line
Bohmian mechanics, a hydrodynamic formulation of quantum mechanics, relies on
the concept of trajectory, which evolves in time in compliance with dynamical
information conveyed by the wave function. Here this appealing idea is
considered to analyze both classical and quantum interference, thus providing
an alternative and more intuitive framework to understand the time-evolution of
waves, either in terms of the flow of energy (for mechanical waves, sound
waves, electromagnetic waves, for instance) or, analogously, the flow of
probability (quantum waves), respectively. Furthermore, this procedure also
supplies a more robust explanation of interference phenomena, which currently
is only based on the superposition principle. That is, while this principle
only describes how different waves combine and what effects these combinations
may lead to, flow lines provide a more precise explanation on how the energy or
probability propagate in space before, during and after the combination of such
waves, without dealing with them separately (i.e., the combination or
superposition is taken as a whole). In this sense, concepts such as
constructive and destructive interference, typically associated with the
superposition principle, physically correspond to more or less dense swarms of
(energy or probability) flow lines, respectively. A direct consequence of this
description is that, when considering the distribution of electromagnetic
energy flow lines behind two slits, each one covered by a differently oriented
polarizer, it is naturally found that external observers' information on the
slit crossed by single photons (understood as energy parcels) is totally
irrelevant for the existence of interference fringes, in striking contrast with
what is commonly stated and taught.Comment: 15 pages, 3 figure
Full quantum mechanical analysis of atomic three-grating Mach-Zehnder interferometry
Atomic three-grating Mach-Zehnder interferometry constitutes an important
tool to probe fundamental aspects of the quantum theory. There is, however, a
remarkable gap in the literature between the oversimplified models and robust
numerical simulations considered to describe the corresponding experiments.
Consequently, the former usually lead to paradoxical scenarios, such as the
wave-particle dual behavior of atoms, while the latter make difficult the data
analysis in simple terms. Here these issues are tackled by means of a simple
grating working model consisting of evenly-spaced Gaussian slits. As is shown,
this model suffices to explore and explain such experiments both analytically
and numerically, giving a good account of the full atomic journey inside the
interferometer, and hence contributing to make less mystic the physics
involved. More specifically, it provides a clear and unambiguous picture of the
wavefront splitting that takes place inside the interferometer, illustrating
how the momentum along each emerging diffraction order is well defined even
though the wave function itself still displays a rather complex shape. To this
end, the local transverse momentum is also introduced in this context as a
reliable analytical tool. The splitting, apart from being a key issue to
understand atomic Mach-Zehnder interferometry, also demonstrates at a
fundamental level how wave and particle aspects are always present in the
experiment, without incurring in any contradiction or interpretive paradox. On
the other hand, at a practical level, the generality and versatility of the
model and methodology presented, makes them suitable to attack analogous
problems in a simple manner after a convenient tuning.Comment: 17 pages, 6 figures (remarkably improved version
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