Synchrony breakdown and noise-induced oscillation death in ensembles of serially connected spin-torque oscillators

We consider collective dynamics in the ensemble of serially connected spin-torque oscillators governed by the Landau-Lifshitz-Gilbert-Slonczewski magnetization equation. Proximity to homoclinicity hampers synchronization of spin-torque oscillators: when the synchronous ensemble experiences the homoclinic bifurcation, the Floquet multiplier, responsible for the temporal evolution of small deviations from the ensemble mean, diverges. Depending on the configuration of the contour, sufficiently strong common noise, exemplified by stochastic oscillations of the current through the circuit, may suppress precession of the magnetic field for all oscillators. We derive the explicit expression for the threshold amplitude of noise, enabling this suppression.Comment: 12 pages, 13 figure

The Power of the Past. Socio-Cultural Foundations of Retromania in Russia at the Turn of the Twentieth and the Twenty-First Centuries

This article defines and analyzes the phenomenon of retromania in the Russian cultural consciousness. The dominance of the past in the Russian collective consciousness is widely considered to have its roots in the Soviet experience of the twentieth century as part of the world historic experience of the age. In this study, its challenging, of-crisis-proportions semantic character is revealed; together with a material and spiritual-and-soulful weight that creates a strong magnetic pull, i.e. a kind of addiction for its bearers. With retromania, the ‘energy intensity’ of its substance, significance and burden, produced a deep although unconscious fatigue in the bearers of the experience – former Soviet people with a shared socio-cultural past. This is often transformed into a sense of impotence with regards to the present and the future, acting as an attribute and symptom of the fundamental anthropological crisis which is an integral outcome of the Soviet civilization. Finally, the dependence of retromania on both the nature of the Russian present and uncertainty of the future is shown. Keywords: retromania, past, present, future, past historical experiences, its semantic, material and energy components, gravity pull of the Soviet experience and fundamental fatigue generated by it

Order-by-disorder in classical oscillator systems

We consider classical nonlinear oscillators on hexagonal lattices. When the coupling between the elements is repulsive, we observe coexisting states, each one with its own basin of attraction. These states differ by their degree of synchronization and by patterns of phase-locked motion. When disorder is introduced into the system by additive or multiplicative Gaussian noise, we observe a non-monotonic dependence of the degree of order in the system as a function of the noise intensity: intervals of noise intensity with low synchronization between the oscillators alternate with intervals where more oscillators are synchronized. In the latter case, noise induces a higher degree of order in the sense of a larger number of nearly coinciding phases. This order-by-disorder effect is reminiscent to the analogous phenomenon known from spin systems. Surprisingly, this non-monotonic evolution of the degree of order is found not only for a single interval of intermediate noise strength, but repeatedly as a function of increasing noise intensity. We observe noise-driven migration of oscillator phases in a rough potential landscape.Comment: 12 pages, 13 figures; comments are welcom

Steady Stokes flow with long-range correlations, fractal Fourier spectrum, and anomalous transport

We consider viscous two-dimensional steady flows of incompressible fluids past doubly periodic arrays of solid obstacles. In a class of such flows, the autocorrelations for the Lagrangian observables decay in accordance with the power law, and the Fourier spectrum is neither discrete nor absolutely continuous. We demonstrate that spreading of the droplet of tracers in such flows is anomalously fast. Since the flow is equivalent to the integrable Hamiltonian system with 1 degree of freedom, this provides an example of integrable dynamics with long-range correlations, fractal power spectrum, and anomalous transport properties.Comment: 4 pages, 4 figures, published in Physical Review Letter