Nonlocal Dynamics Research Articles

Dynamics of the Kuramoto equation with spatially distributed control

We consider the scalar complex equation with spatially distributed control. Its dynamical properties are studied by asymptotic methods when the control coefficient is either sufficiently large or sufficiently small and the function of distribution is either almost symmetric or significantly nonsymmetric relative to zero. In all cases we reduce original equation to quasinormal form – the family of special parabolic equations, which do not contain big and small parameters, which nonlocal dynamics determines the behaviour of solutions of the original equation.

Ferroelectric control of anisotropic damping in multiferroic tunnel junctions

The magnetoelectric effect on nonlocal magnetization dynamics is theoretically investigated in normal-metal/ferroelectric-insulator/ferromagnetic tunnel junctions. In addition to the Rashba spin-orbit interaction (SOI) originating from loss of parity symmetry at the interfaces, the topology of interfacial spiral spins triggered by ferroelectric polarization acts with an effective SOI that is electrically controllable. These spin-dependent interactions result in an anisotropic Gilbert damping with C2v symmetry. The findings are of a direct relevance for the utilization of composite multiferroics for devices that rely on electrically controlled magnetic switching.

Uniform dynamics for Fisher-KPP propagation driven by a line of fast diffusion under a singular limit

The purpose of this paper is to understand the links between a model introduced in 2012 by Berestycki, Roquejoffre and Rossi and a nonlocal model studied by the author in 2014. The general question is to investigate the influence of a line of fast diffusion on Fisher-KPP propagation. In the initial model, the exchanges are modeled by a Robin boundary condition, whereas in the nonlocal model the exchanges are described by integral terms. For both models was showed the existence of an enhanced spreading in the direction of the line. One way to retrieve the local model from the nonlocal one is to consider integral terms tending to Dirac masses. The question is then how the dynamics given by the nonlocal model resembles the local one. We show here that the nonlocal dynamics tends to the local one in a rather strong sense.

Local Dynamics of the Two-Component Singular Perturbed Systems of Parabolic Type

This paper considers the behavior of solutions from the neighborhood of an equilibrium state of nonlinear two-component parabolic problems with diffusion matrixes of one or two eigenvalues to zero. It has been shown that problems related to stability have infinite dimension. Reported here is the development of an algorithm that constructs universal families of nonlinear boundary-value problems which do not contain small parameters and whose nonlocal dynamics describes local dynamics of original boundary-value problems. In addition, an exhaustive set of universal systems for two-component parabolic equations is presented. It is concluded that a hyper multistability phenomenon is one characteristic of these systems.

Constraint algebra of general relativity from a formal continuum limit of canonical tensor model

Canonical tensor model (CTM for short below) is a rank-three tensor model formulated as a totally constrained system in the canonical formalism. In the classical case, the constraints form a first-class constraint Poisson algebra with structures similar to that of the ADM formalism of general relativity, qualifying CTM as a possible discrete formalism for quantum gravity. In this paper, we show that, in a formal continuum limit, the constraint Poisson algebra of CTM with no cosmological constant exactly reproduces that of the ADM formalism. To this end, we obtain the expression of the metric tensor field in general relativity in terms of one of the dynamical rank-three tensors in CTM, and determine the correspondence between the constraints of CTM and those of the ADM formalism. On the other hand, the cosmological constant term of CTM seems to induce non-local dynamics, and is inconsistent with an assumption about locality of the continuum limit.

CORPORATE DYNAMICS OF SYSTEMS OF LOGISTIC DELAY EQUATIONS WITH LARGE DELAY CONTROL

A system of two logistic equations with delay coupled by delayed control is considered. It is shown that in the case of a sufficiently large delay control coefficient the problem of the dynamics of the initial systems is reduced to studying the non-local dynamics of special families of partial differential equations that do not contain small and large parameters. New interesting dynamic phenomena were discovered on the basis of the results of numerical analysis. Systems of three logistic delay equations with two types of ”diffusion” relation were considered. Special families of partial differential equations that do not contain small and large parameters were also constructed for each of these systems. The results of the study of the original equations dynamic properties are presented. It is shown that the difference in the dynamics of the considered systems of three equations may be of a fundamental nature.

Spin-charge transport driven by magnetization dynamics on the disordered surface of doped topological insulators

We theoretically study the spin and charge generations along with the electron transport on a disordered surface of a doped three-dimensional topological insulator/magnetic insulator junction by using Green's function techniques. We find that the spin and charge currents are induced by not only local, but also nonlocal magnetization dynamics through nonmagnetic impurity scattering on the disordered surface of the doped topological insulator. We also clarify that the spin current as well as charge density are induced by spatially inhomogeneous magnetization dynamics, and the spin current diffusively propagates on the disordered surface. Using these results, we discuss both local and nonlocal spin torques before and after the spin and spin-current generations on the surface, and provide a procedure to detect the spin current.

Dynamics of Measurement-Induced Non-Locality and Geometric Measure of Discord in a Two-Qubit Heisenberg XY Chain

By taking into account the Dzyaloshinsky-Moriya (DM) interaction under uniform magnetic field, quantum correlation behaviors measured by the measurement-induced nonlocality (MIN) and the geometric measure of discord (GMOD) in a two-qubit XY model are investigated in detail. Turning the different parameters can lead the two kinds of measurements to present different properties. For example, increasing the parameter B(uniform magnetic field), the existing region of MIN is larger than GMOD; MIN can appear the phenomenon of monotonous reduction when the parameter D(Dzyaloshinsky-Moriya interaction) is smaller than one threshold value, while GMOD cannot; MIN monotonously reduces with enhancive value of T(temperature), while GMOD initial experiences a slightly increasing and then decreases. One interesting point is that the more obvious and complicated difference between them are shown from the initial values. This property is both true for the zero temperature and the finite temperature. Through analyzing the limit case of the temperature approaching zero, the analytic solutions give the detailed reasons why have different effect on the initial values. Moreover, from the analytic solutions, we know the initial value of MIN is always larger than or equal to GMOD.

Dynamics of the logistic equation with delay

The logistic equation supplemented with a summand characterizing delay is considered. The local and nonlocal dynamics of this equation are studied. For equations with delay, we use the standard Andronov—Hopf bifurcation methods and the asymptotic method developed by the author and based on the construction of special evolution equations defining the local dynamics of the equations containing delay. In addition, we study the existence and methods of constructing the asymptotics of nonlocal relaxation cycles. A comparison of the results obtained with those for the Hutchinson equation and some of its generalizations is given.

ChemInform Abstract: Microscopic Studies of Nonlocal Spin Dynamics and Spin Transport (Invited)

AbstractReview: 25 refs.

Non-local dynamics governing the self-induced motion of a planar vortex filament

While the Hasimoto planar vortex filament is one of the few exact solutions to the local induction approximation (LIA) approximating the self-induced motion of a vortex filament, it is natural to wonder whether such a vortex filament solution would exist for the non-local Biot-Savart dynamics exactly governing the filament motion, and if so, whether the non-local effects would drastically modify the solution properties. Both helical vortex filaments and vortex rings are known to exist under both the LIA and non-local Biot-Savart dynamics; however, the planar filament is a bit more complicated. In the present paper, we demonstrate that a planar vortex filament solution does exist for the non-local Biot-Savart formulation, provided that a specific non-linear integral equation (governing the spatial structure of such a filament) has a non-trivial solution. By using the Poincaré–Lindstedt method, we are able to obtain an accurate analytical approximation to the solution of this integral equation under physically reasonable assumptions. To obtain these solutions, we approximate local effects near the singularity of the integral equation using the LIA and non-local effects using the Biot-Savart formulation. Mathematically, the results constitute an analytical solution to an interesting nonlinear singular integro-differential equation in space and time variables. Physically, these results show that planar vortex filaments exist and maintain their forms under the non-local Biot-Savart formulation, as one would hope. Due to the regularization approach utilized, we are able to compare the structure of the planar filaments obtained under both LIA and Biot-Savart formulations in a rather straightforward manner, in order to determine the role of the non-locality on the structure of the planar filament.

English

The work analyzes the compatibility between the classical freedom, the local relativistic causality and the non-local behavior of quantum mechanics in the frame of the stochastic approach of the quantum hydrodynamic analogy (SQHA). The work describes the role of the quantum potential in generating the quantum non-local dynamics in a fluctuating environment. The analysis shows that it is possible to maintain the concept of classical freedom between far away weakly bounded systems (moderate non-locality) as well as to make compatible the uncertainty principle with the relativistic postulate of invariance of light speed. The work shows that the paradox of instantaneous quantum non local behavior at infinite distances of the standard formalism is an artifact due to the non-relativistic non-stochastic ambit of such theory where the light speed is infinite and the non-local interaction owns an infinite range of action. The work envisages that the SQHA can possibly lead to a fully theoretically self-standing quantum mechanics where the wave function collapse, during a measurement process, can be described by the theory itself without empirical postulates. Under this light the paper discusses the need of searching for (both local and non-local) hidden variables quantum mechanics as well as the need of superluminal communications in quantum experiments. The analysis shows that all these hypotheses are attempts of interpreting the outputs of quantum measurements that cannot be fully explained by the semi-empirical formalism of quantum mechanics, based on the statistical postulates of the measuring process as well as the existence of a classical observer. A two photon experiment is discussed to the light of the SQHA approach. Key words: Quantum non-locality, superluminal transmission of quantum information, classical freedom, local relativistic causality, Einstein, Podolsky, and Rosen (EPR) paradox, macroscopic quantum decoherence, Bell’s inequalities, quantum hydrodynamic analogy.

A concurrent multiscale micromorphic molecular dynamics

In this work, we have derived a multiscale micromorphic molecular dynamics (MMMD) from first principle to extend the (Andersen)-Parrinello-Rahman molecular dynamics to mesoscale and continuum scale. The multiscale micromorphic molecular dynamics is a con-current three-scale dynamics that couples a fine scale molecular dynamics, a mesoscale micromorphic dynamics, and a macroscale nonlocal particle dynamics together. By choosing proper statistical closure conditions, we have shown that the original Andersen-Parrinello-Rahman molecular dynamics is the homogeneous and equilibrium case of the proposed multiscale micromorphic molecular dynamics. In specific, we have shown that the Andersen-Parrinello-Rahman molecular dynamics can be rigorously formulated and justified from first principle, and its general inhomogeneous case, i.e., the three scale con-current multiscale micromorphic molecular dynamics can take into account of macroscale continuum mechanics boundary condition without the limitation of atomistic boundary condition or periodic boundary conditions. The discovered multiscale scale structure and the corresponding multiscale dynamics reveal a seamless transition from atomistic scale to continuum scale and the intrinsic coupling mechanism among them based on first principle formulation.

Fourth post-Newtonian effective one-body dynamics

The conservative dynamics of gravitationally interacting two-point-mass systems has been recently determined at the fourth post-Newtonian (4PN) approximation [T.Damour, P.Jaranowski, and G.Sch\"afer, Phys. Rev. D 89, 064058 (2014)], and found to be nonlocal in time. We show how to transcribe this dynamics within the effective one-body (EOB) formalism. To achieve this EOB transcription, we develop a new strategy involving the (infinite-)order-reduction of a nonlocal dynamics to an ordinary action-angle Hamiltonian. Our final, equivalent EOB dynamics comprises two (local) radial potentials, $A(r)$ and $\bar{D}(r)$, and a nongeodesic mass-shell contribution $Q(r,p_r)$ given by an infinite series of even powers of the radial momentum $p_r$. Using an effective action technique, we complete our 4PN-level results by deriving two different, higher-order conservative contributions linked to tail-transported hereditary effects: the 5PN-level EOB logarithmic terms, as well as the 5.5PN-level, half-integral terms. We compare our improved analytical knowledge to previous, numerical gravitational-self-force computation of precession effects.

Local and nonlocal dynamics in superfluid turbulence

In turbulent superfluid He II, the quantized vortex lines interact via the classical Biot-Savart law to form a complicated vortex tangle. We show that vortex tangles with the same vortex line density will have different energy spectra, depending on the normal fluid which feeds energy into the superfluid component, and identify the spectral signature of two forms of superfluid turbulence: Kolmogorov tangles and Vinen tangles. By decomposing the superfluid velocity field into local and nonlocal contributions, we find that in Vinen tangles the motion of vortex lines depends mainly on the local curvature, whereas in Kolmogorov tangles the long-range vortex interaction is dominant and leads to the formation of clustering of lines, in analogy to the ``worms'' of ordinary turbulence.

Line emission radiation during early-time interaction of an intense short laser pulse with an ultrathin planar aluminum target

The interaction of an intense short laser pulse with an ultrathin planar aluminum foil is investigated with a fully relativistic particle-in-cell model self-consistently coupled to an atomic dynamics model describing the non-local thermodynamic equilibrium level population dynamics and radiative behavior of a plasma evolving on a picosecond timescale. For typical experimental conditions, laser pulses with energy 1 J, intensity 1020 W cm−2, and duration 40 fs, a synthetic spectrum for the emission lines is generated as a function of time for lines emanating in the hydrogen- and helium-like ionization stages. It is found that Heα, Heβ, Lyα, and Lyβ lines have intensities above the Bremsstrahlung continuum and could serve as diagnostics for the evolving plasma condition.

Microscopic studies of nonlocal spin dynamics and spin transport (invited)

Understanding the behavior of spins coupling across interfaces in the study of spin current generation and transport is a fundamental challenge that is important for spintronics applications. The transfer of spin angular momentum from a ferromagnet into an adjacent normal material as a consequence of the precession of the magnetization of the ferromagnet is a process known as spin pumping. We find that, in certain circumstances, the insertion of an intervening normal metal can enhance spin pumping between an excited ferromagnetic magnetization and a normal metal layer as a consequence of improved spin conductance matching. We have studied this using inverse spin Hall effect and enhanced damping measurements. Scanned probe magnetic resonance techniques are a complementary tool in this context offering high resolution magnetic resonance imaging, localized spin excitation, and direct measurement of spin lifetimes or damping. Localized magnetic resonance studies of size-dependent spin dynamics in the absence of lithographic confinement in both ferromagnets and paramagnets reveal the close relationship between spin transport and spin lifetime at microscopic length scales. Finally, detection of ferromagnetic resonance of a ferromagnetic film using the photoluminescence of nitrogen vacancy spins in neighboring nanodiamonds demonstrates long-range spin transport between insulating materials, indicating the complexity and generality of spin transport in diverse, spatially separated, material systems.

Nonlocal ultrafast demagnetization dynamics of Co/Pt multilayers by optical field enhancement

The influence on ultrafast demagnetization dynamics of metallic nano-structured gratings deposited on thin films of magnetic Co/Pt multilayers is investigated by the time-resolved optical Kerr effect. Depending on the polarization of the pump pulse, a pronounced enhancement of the demagnetization amplitude is found. Calculation of the inhomogeneous optical field distribution due to plasmon interaction and time-dependent solutions of the coupled electron, lattice, and spin temperatures in two dimensions show good agreement with the experimental data, as well as giving evidence of non-local demagnetization dynamics due to electron diffusion.

How trading volume responds to return in financial dynamics?

How trading volume responds to price return is investigated by the return–volume correlation dynamics, based on the daily data of two typical financial markets, i.e., the Chinese and the United States stock markets. Whereas the price returns being observed to be positively correlated with the trading volumes for the Chinese stock markets, a significant transition from the positive correlation to negative correlation is revealed for the United States stock markets. Leverage and anti-leverage effects of the return–volume correlations are found for the last decade of the United States stock markets and the Chinese stock markets, respectively. Nonlocal dynamics further suggests an adverse correlation for the two markets. A retarded herding model is introduced to describe the leverage and anti-leverage effects. Our work may shed a new light on the financial dynamics differing in the mature and emerging markets.

The Collapse and Revival of Bell-nonlocaliy for Continuous Variables

We study the quantum nonlocality dynamics of pair coherent states in the double Jaynes-Cummings model. It is shown that the Bell-inequality violation can be fully destroyed in a finite time and then recovered. The inequality violation can obtain better recovery when only one atom couples to either of the cavity fields. Besides, the correlation property of cavity fields is more feasible affected when the atom interacts resonantly with the second cavity field. The difference in the number of photons of the two modes may play an important role in the case of resonant interaciton especially.