Aharonov-Bohm Type Forces Between Magnetic Fluxons

Forces related to A-B phases between fluxons with $\Phi=\alpha\Phi_0\ \ \$ $\alpha\ne integer$ are discussed. We find a $\alpha^2\ln(r)$ type interaction screened on a scale $\lambda_s$. The forces exist only when the fluxons are actually immersed in the region with non vanishing charge density and are periodic in $\alpha$. 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 $d$-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 $d>2$ 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 $d$ and 2d. In general we show that the alphabet size grows in "steps" with the possible values $d, d+1, ..., d^2-2$. 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 $k>k_c$. Nevertheless, it is shown that Hawking radiation is still emitted if free field modes with $k>k_c$ are in their ground state.Comment: 13 Pages, 3 figures, Revtex with epsf macro