Mobility of high-power solitons in saturable nonlinear photonic lattices

We theoretically study the properties of one-dimensional nonlinear saturable photonic lattices exhibiting multiple mobility windows for stationary solutions. The effective energy barrier decreases to a minimum in those power regions where a new intermediate stationary solution appears. As an application, we investigate the dynamics of high-power gaussian-like beams finding several regions where the light transport is enhanced.Comment: 3 pages, 3 figures, to be published in Optics Letter

Stationary discrete solitons in circuit QED

We demonstrate that stationary localized solutions (discrete solitons) exist in a one dimensional Bose-Hubbard lattices with gain and loss in the semiclassical regime. Stationary solutions, by defi- nition, are robust and do not demand for state preparation. Losses, unavoidable in experiments, are not a drawback, but a necessary ingredient for these modes to exist. The semiclassical calculations are complemented with their classical limit and dynamics based on a Gutzwiller Ansatz. We argue that circuit QED architectures are ideal platforms for realizing the physics developed here. Finally, within the input-output formalism, we explain how to experimentally access the different phases, including the solitons, of the chain.Comment: 10 pages including appendix, 7 figure

Compactification tuning for nonlinear localized modes in sawtooth lattices

We discuss the properties of nonlinear localized modes in sawtooth lattices, in the framework of a discrete nonlinear Schrödinger model with general on-site nonlinearity. Analytic conditions for existence of exact compact three-site solutions are obtained, and explicitly illustrated for the cases of power-law (cubic) and saturable nonlinearities. These nonlinear compact modes appear as continuations of linear compact modes belonging to a flat dispersion band. While for the linear system a compact mode exists only for one specific ratio of the two different coupling constants, nonlinearity may lead to compactification of otherwise noncompact localized modes for a range of coupling ratios, at some specific power. For saturable lattices, the compactification power can be tuned by also varying the nonlinear parameter. Introducing different on-site energies and anisotropic couplings yields further possibilities for compactness tuning. The properties of strongly localized modes are investigated numerically for cubic and saturable nonlinearities, and in particular their stability over large parameter regimes is shown. Since the linear flat band is isolated, its compact modes may be continued into compact nonlinear modes both for focusing and defocusing nonlinearities. Results are discussed in relation to recent realizations of sawtooth photonic lattices.The research has been performed with support from the Swedish Research Council within the Swedish Research Links program, 348-2013-6752. U.N. appreciates the Spanish government projects FIS 2011-25167 and FPDI-2013-18422 as well as the Aragon project (Grupo FENOL). R.A.V. acknowledges support from Programa ICM grant RC130001, Programa de Financiamiento Basal de CONICYT (FB0824/2008), and FONDECYT Grant No. 1151444.Peer Reviewe

Un problema de bosones que interaccionan. Cálculos analíticos y numéricos

El trabajo consiste en un estudio de un sistema de bosones interactuantes. El objetivo primordial es la obtención de un método numérico que permita resolver un caso no lineal, no resoluble analíticamente, para un arreglo de bosones en forma de diente de sierra. Se empezará por recordar algunos conceptos básicos del oscilador armónico cuántico como los operadores de creación y destrucción. El Hamiltoniano del sistema conmuta con el operador número, lo cual definirá los autoestados que usaremos a lo largo de todo el trabajo. Primero obtendremos en el límite lineal las bandas de energía para un arreglo unidimensional y luego para un caso intermedio entre una y dos dimensiones, el arreglo en forma de diente de sierra. Obtendremos las condiciones necesarias para la existencia de bandas planas, observándose que no siempre estas existen. Tras todo ello empezaremos a desarrollar los métodos numéricos. Analizaremos el sistema en el caso de una excitación, observando dependencia del tamaño finito. A continuación desarrollamos un primer método conceptualmente sencillo, pero muy deficiente. Ello nos llevará a desarrollar un segundo método, el definitivo, el cual nos permitirá ahorrarnos mucho tiempo de cálculo. Para analizar resolveremos por fin el Hamiltoniano no lineal. Observaremos la ruptura de la degeneración de las bandas planas del caso lineal. Así, habremos estudiado el sistema primero en un caso de un arreglo sencillo de una dimensión pasando después a un arreglo a caballo entre una y dos dimensiones. Centrándonos en un inicio en el caso lineal y sus propiedades para terminar resolviendo, ahora numéricamente, el caso no lineal

Nanometric constrictions in superconducting coplanar waveguide resonators

We report on the design, fabrication and characterization of superconducting coplanar waveguide resonators with nanoscopic constrictions. By reducing the size of the center line down to 50 nm, the radio frequency currents are concentrated and the magnetic field in its vicinity is increased. The device characteristics are only slightly modified by the constrictions, with changes in resonance frequency lower than 1% and internal quality factors of the same order of magnitude as the original ones. These devices could enable the achievement of higher couplings to small magnetic samples or even to single molecular spins and have applications in circuit quantum electrodynamics, quantum computing and electron paramagnetic resonance.Comment: 4 pages, 4 figure

From Josephson junction metamaterials to tunable pseudo-cavities

arXiv:1305.4844v1The scattering through a Josephson junction (JJ) interrupting a superconducting line is revisited including power leakage. We also discuss how to make tunable and broadband resonant mirrors by concatenating junctions. As an application, we show how to construct cavities using these mirrors, thus connecting two research fields: JJ quantum metamaterials and coupled-cavity arrays. We finish by discussing the first nonlinear corrections to the scattering and their measurable effects. © 2013 IOP Publishing Ltd.This work was supported by Spanish government projects FIS2009-10061, and FIS2011-25167 conanced by FEDER funds. We thanks Aragon government support to group FENOL, CAM research consortium QUITEMAD and PROMISCE European project.Peer Reviewe