1,542 research outputs found
Aharonov-Bohm Type Forces Between Magnetic Fluxons
Forces related to A-B phases between fluxons with
are discussed. We find a type interaction
screened on a scale . The forces exist only when the fluxons are
actually immersed in the region with non vanishing charge density and are
periodic in . We briefly comment on the problem of observing such
forces.Comment: 10 pages, latex, no fi
Justification of application of nonlinear viscoelasticity model of Rabotnov's model type in creep problems
The relationship between the components of the strain tensor, stress tensor and time is given by the defining equations of the hereditary type, which are written based on the hypothesis of proportionality of the deviators. Thin-walled tubular low-pressure polyethylene elements are considered as the object of research. The scope of the model is substantiated based on the hypothesis of the existence of a single diagram of instantaneous deformation and a single diagram of long-term deformation. The invariance of the tensile and torsion diagrams with respect to the stress state is checked. The region of nonlinear elastic deformation is determined. The defining equations of the model contain a set of functions and coefficients determined from the basic experiments. A method for determining the parameters of heredity kernels of nonlinear viscoelastic materials under complex stress state has been developed. The nonlinearity of viscoelastic properties is given by equations of the Rabotnov's model type. The method is based on the relations between the creep kernels obtained under conditions of complex stress state and the creep kernels under one-dimensional stress state. The method is tested experimentally on the problems of calculating creep deformations under combined loading of thin-walled tubular elements made of low-pressure polyethylene.
Pages of the article in the issue: 111 - 114
Language of the article: Ukrainia
Entanglement of Solitons in the Frenkel-Kontorova Model
We investigate entanglement of solitons in the continuum-limit of the
nonlinear Frenkel-Kontorova chain. We find that the entanglement of solitons
manifests particle-like behavior as they are characterized by localization of
entanglement. The von-Neumann entropy of solitons mixes critical with
noncritical behaviors. Inside the core of the soliton the logarithmic increase
of the entropy is faster than the universal increase of a critical field,
whereas outside the core the entropy decreases and saturates the constant value
of the corresponding massive noncritical field. In addition, two solitons
manifest long-range entanglement that decreases with the separation of the
solitons more slowly than the universal decrease of the critical field.
Interestingly, in the noncritical regime of the Frenkel-Kontorova model,
entanglement can even increase with the separation of the solitons. We show
that most of the entanglement of the so-called internal modes of the solitons
is saturated by local degrees of freedom inside the core, and therefore we
suggest using the internal modes as carriers of quantum information.Comment: 16 pages, 22 figure
Critical and noncritical long range entanglement in the Klein-Gordon field
We investigate the entanglement between two separated segments in the vacuum
state of a free 1D Klein-Gordon field, where explicit computations are
performed in the continuum limit of the linear harmonic chain. We show that the
entanglement, which we measure by the logarithmic negativity, is finite with no
further need for renormalization. We find that the quantum correlations decay
much faster than the classical correlations as in the critical limit long range
entanglement decays exponentially for separations larger than the size of the
segments. As the segments become closer to each other the entanglement diverges
as a power law. The noncritical regime manifests richer behavior, as the
entanglement depends both on the size of the segments and on their separation.
In correspondence with the von Neumann entropy long-range entanglement also
distinguishes critical from noncritical systems
Not So SuperDense Coding - Deterministic Dense Coding with Partially Entangled States
The utilization of a -level partially entangled state, shared by two
parties wishing to communicate classical information without errors over a
noiseless quantum channel, is discussed. We analytically construct
deterministic dense coding schemes for certain classes of non-maximally
entangled states, and numerically obtain schemes in the general case. We study
the dependency of the information capacity of such schemes on the partially
entangled state shared by the two parties. Surprisingly, for it is
possible to have deterministic dense coding with less than one ebit. In this
case the number of alphabet letters that can be communicated by a single
particle, is between and 2d. In general we show that the alphabet size
grows in "steps" with the possible values . We also find
that states with less entanglement can have greater communication capacity than
other more entangled states.Comment: 6 pages, 2 figures, submitted to Phys. Rev.
Superfast Cooling
Currently laser cooling schemes are fundamentally based on the weak coupling
regime. This requirement sets the trap frequency as an upper bound to the
cooling rate. In this work we present a numerical study that shows the
feasibility of cooling in the strong coupling regime which then allows cooling
rates that are faster than the trap frequency with state of the art
experimental parameters. The scheme we present can work for trapped atoms or
ions as well as mechanical oscillators. It can also cool medium size ions
chains close to the ground state.Comment: 5 pages 4 figure
Origin of the Thermal Radiation in a Solid-State Analog of a Black-Hole
An effective black-hole-like horizon occurs, for electromagnetic waves in
matter, at a surface of singular electric and magnetic permeabilities. In a
physical dispersive medium this horizon disappears for wave numbers with
. Nevertheless, it is shown that Hawking radiation is still emitted if
free field modes with are in their ground state.Comment: 13 Pages, 3 figures, Revtex with epsf macro
- …