Control of wavepacket spreading in nonlinear finite disordered lattices

In the absence of nonlinearity all normal modes (NMs) of a chain with disorder are spatially localized (Anderson localization). We study the action of nonlinearity, whose strength is ramped linearly in time. It leads to a spreading of a wavepacket due to interaction with and population of distant NMs. Eventually the nonlinearity induced frequency shifts take over, and the wavepacket becomes selftrapped. On finite chains a critical ramping speed is obtained, which separates delocalized final states from localized ones. The critical value depends on the strength of disorder and is largest when the localization length matches the system size.Comment: 7 pages, 4 figures, submitted to PR

A simple method to construct Flat Band lattices

We develop a simple and general method to construct arbitrary Flat Band lattices. We identify the basic ingredients behind zero-dispersion bands and develop a method to construct extended lattices based on a consecutive repetition of a given mini-array. The number of degenerated localized states is defined by the number of connected mini-arrays times the number of modes preserving the symmetry at a given connector site. In this way, we create one or more (depending on the lattice geometry) complete degenerated Flat Bands for quasi-one and two-dimensional systems. We probe our method by studying several examples, and discuss the effect of additional interactions like anisotropy or nonlinearity. At the end, we test our method by studying numerically a ribbon lattice using a continuous description.Comment: 11 pages, 11 figure

Fano blockade by a Bose-Einstein condensate in an optical lattice

We study the transport of atoms across a localized Bose-Einstein condensate in a one-dimensional optical lattice. For atoms scattering off the condensate we predict total reflection as well as full transmission for certain parameter values on the basis of an exactly solvable model. The findings of analytical and numerical calculations are interpreted by a tunable Fano-like resonance and may lead to interesting applications for blocking and filtering atom beams.Comment: 4 pages, 4 figures (fig4 was resized for arXiv

Financialising the State : Recent development in fiscal and monetary policy

Understanding the nature of state financialisation is crucial to ensure definancialisation efforts are successful. This paper provides a structured overview of the emerging literature on financialisation and the state. We define financialisation of the state broadly as the changed relationship between the state, understood as sovereign with duties and accountable towards its citizens, and financial markets and practices, in ways that can diminish those duties and reduce accountability. We then argue that there are four ways in which financialisation works in and through public institutions and policies: adoption of financial motives, advancing financial innovation, embracing financial accumulation strategies, and directly financialising the lives of citizens. Organising our review around the two main policy fields of fiscal and monetary policy, four definitions of financialisation in the context of public policy and institutions emerge. When dealing with public expenditure on social provisions financialisation most often refers to the transformation of public services into the basis for actively traded financial assets. In the context of public revenue, financialisation describes the process of creating and deepening secondary markets for public debt, with the state turning into a financial market player. Finally, in the realm of monetary policy financial deregulation is perceived to have paved the way for financialisation, while inflation targeting and the encouragement, or outright pursuit, of market-based short-term liquidity management among financial institutions constitute financialised policies

Strong asymmetry for surface modes in nonlinear lattices with long-range coupling

We analyze the formation of localized surface modes on a nonlinear cubic waveguide array in the presence of exponentially-decreasing long-range interactions. We find that the long-range coupling induces a strong asymmetry between the focusing and defocusing cases for the topology of the surface modes and also for the minimum power needed to generate them. In particular, for the defocusing case, there is an upper power threshold for exciting staggered modes, which depends strongly on the long-range coupling strength. The power threshold for dynamical excitation of surface modes increase (decrease) with the strength of long-range coupling for the focusing (defocusing) cases. These effects seem to be generic for discrete lattices with long-range interactions.Comment: 4 pages, 5 figures, submitted for publicatio

Two-color discrete localized modes and resonant scattering in arrays of nonlinear quadratic optical waveguides

We analyze the properties and stability of two-color discrete localized modes in arrays of channel waveguides where tunable quadratic nonlinearity is introduced as a nonlinear defect by periodic poling of a single waveguide in the array. We show that, depending on the value of the phase mismatch and the input power, such two-color defect modes can be realized in three different localized states. We also study resonant light scattering in the arrays with the defect waveguide.Comment: 10 pages, 3 figures, published in PR