Instability of dispersion-managed solitons in a system with filtering

Unstable behavior of dispersion-managed (DM) solitons in a system with lumped filtering is numerically studied. A variational analysis shows that the system cannot have stable fixed DM soliton solutions when the filter location is improperly chosen. This is because of the unique dynamics of the spectral behavior of DM solitons, which differs from that of standard solitons in fibers with constant dispersion. The instability is confirmed by numerical simulations with and without sliding center frequencies of the filters.     

The emergence of network communities by the action of coevolving market agents

The agent-based multileader model of the stock price dynamics on the directed evolving complex network is studied by direct simulation. The resulting stationary regime follows from the balance of extremal dynamics, adaptivity of the strategic variables, and reconnection rules. For given parametric combination, the network displays small-world phenomenon with high clustering coefficients and power-law node degree distribution. The fitness exploration by the mechanism of repeated random walk is used to violate dominance of centralized leadership. The simulation suggests that ultra slow dynamics of fitness implies explanation of the long-time volatility of the log-price returns. The text was submitted by the authors in English.     

Instability of the trivelpiece mode in a beam-plasma system

Spatial growth of an electrostatic wave is observed in a beam-plasma system, and can be explained consistently as an instability of the Trivelpiece mode.     

磁光双稳系统的非稳特性

从具有延时反馈回路的磁光双稳系统的动力学方程出发,讨论了该系统的一些非稳特性,研究了磁光双稳系统的消光比对该系统非稳特性的影响.     

Controllable quantum information network with a superconducting system

We propose a controllable and scalable architecture for quantum information processing using a superconducting system network, which is composed of current-biased Josephson junctions (CBJJs) as tunable couplers between the two superconducting transmission line resonators (TLRs), each coupling to multiple superconducting qubits (SQs). We explicitly demonstrate that the entangled state, the phase gate, and the information transfer between any two selected SQs can be implemented, respectively. Lastly, numerical simulation shows that our scheme is robust against the decoherence of the system.     

Bifurcational behavior of potential energy in a particle system

The paper considers a one-dimensional crystal model consisting of pairwise interacting particles. The critical points of potential energy for the crystal system under tension are studied on the assumption that the pair interaction potential has a single minimum. It is shown that new critical points of potential energy appear in a bifurcational manner.     

Quantization of particle system with anomalous moments

A procedure is outlined for Hamiltonization of a particle system with anomalous magnetic moments and presumed electrical dipole moments, in the zero-plane formalism. Hamiltonization is undertaken in the covariant Lorentz gauge A = 0.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 78–81, September, 1987.     

Instability of the tunneling destruction effect in a quasi-periodically driven two-level system

Here we consider the dynamics of a two-level system under an external time-dependent field. We show that in the case of a bichromatic field the dynamical localization effect is strongly sensitive with respect to the commensurability of the driving frequencies. Received 8 May 2002 / Received in final form 4 July 2002 Published online 24 September 2002 RID="a" ID="a"e-mail: Sacchetti@unimo.it     

动态银行网络系统中系统性风险定量计算方法研究

采用复杂网络理论研究银行网络系统中的系统性风险问题已有较多的报道.这些研究大多假设银行网络系统是静态的(银行节点是静态的,银行节点间的借贷关系也是静态的),然后在系统性风险已经累积到爆发的情况下,研究风险爆发后,风险在静态网络系统中的传染与网络结构的关系.然而对于系统性风险如何在银行网络中累积直至爆发的问题的研究还很少.系统风险的累积过程需在动态演化的银行网络系统中才能实现,同时观察风险累积过程需对系统风险进行定量估算.因此,本文首先建立带有宏观经济趋势及多期清算的动态银行网络系统模型;提出系统风险的定量计算方法;最后对系统风险进行仿真计算与分析,得到了系统风险变化曲线,显示了系统风险累积的过程.该研究为定量研究动态银行网络系统的风险累积问题奠定了基础.     

Instability in magnetic materials with a dynamical axion field

It has been pointed out that axion electrodynamics exhibits instability in the presence of a background electric field. We show that the instability leads to a complete screening of an applied electric field above a certain critical value and the excess energy is converted into a magnetic field. We clarify the physical origin of the screening effect and discuss its possible experimental realization in magnetic materials where magnetic fluctuations play the role of the dynamical axion field.     

Damping of coherent betatron oscillations of a charged particle beam in synchrotrons with a feedback system

Decisions of a delay differential equation which describes the dynamics of a charged particle beam in the smoothed approach in synchrotrons with a feedback system are analyzed. Features of the decisions for frequency shifts and decrements of coherent betatron oscillation damping caused by a signal delay in the feedback loop are revealed.     

Instability of a scalar field in a geometry with anisotropic inflation

It is shown that ever-increasing long-wave fluctuations are generated for a light scalar field in metrics which have exponential expansion (inflation) on some coordinates (including Kaluza-Klein models). This result generalizes the well-known result for the de Sitter metric, and may be important in Kaluza-Klein models with dynamical reduction and for the pre-inflationary spacetime foam.     

Kelvin Helmholtz Instability in a Magnetoplasma

Two dimensional transverse Kelvin-Helmholtz (K-H) instability has been studied at the interface between the two fluids (plasma medium) of finite thickness in relative motion to each other. The perturbations on the interface are assumed to be electromagnetic and a dispersion relation is obtained. The interface (boundary) has been found to be unstable for a wide range of perturbation wavelengths (wave numbers kx, ky). It is shown that the modification introduced by electromagnetic (quasi-electrostatic) perturbations in comparison to electrostatic one is to reduce the growth rate of perturbations. The growth rate maximizes when kx = ky. The applications of this study have been discussed to explain some of the observed ionospheric (auroral arc formation) and magnetospheric (unstable magnetopause boundary, hydromagnetic pulsations) phenomena.     

Nonlinear Instability in a Semiclassical Problem

We consider a nonlinear evolution problem with an asymptotic parameter and construct examples in which the linearized operator has spectrum uniformly bounded away from ${{\rm Re}\; z \geq 0 }$ (that is, the problem is spectrally stable), yet the nonlinear evolution blows up in short times for arbitrarily small initial data. We interpret the results in terms of semiclassical pseudospectrum of the linearized operator: despite having the spectrum in ${{\rm Re}\;z < -\gamma_0 < 0 }$ , the resolvent of the linearized operator grows very quickly in parts of the region ${{\rm Re}\;z > 0 }$ . We also illustrate the results numerically.