Solutions of Several Coupled Discrete Models in terms of Lame Polynomials of Order One and Two

Coupled discrete models abound in several areas of physics. Here we provide an extensive set of exact quasiperiodic solutions of a number of coupled discrete models in terms of Lame polynomials of order one and two. Some of the models discussed are (i) coupled Salerno model, (ii) coupled Ablowitz-Ladik model, (iii) coupled saturated discrete nonlinear Schrodinger equation, (iv) coupled phi4 model, and (v) coupled phi6 model. Furthermore, we show that most of these coupled models in fact also possess an even broader class of exact solutions.Comment: 31 pages, to appear in Pramana (Journal of Physics) 201

Solutions of Several Coupled Discrete Models in terms of Lame Polynomials of Arbitrary Order

Coupled discrete models abound in several areas of physics. Here we provide an extensive set of exact quasiperiodic solutions of a number of coupled discrete models in terms of Lam\'e polynomials of arbitrary order. The models discussed are (i) coupled Salerno model, (ii) coupled Ablowitz-Ladik model, (iii) coupled $\phi^4$ model, and (iv) coupled $\phi^6$ model. In all these cases we show that the coefficients of the Lam\'e polynomials are such that the Lam\'e polynomials can be reexpressed in terms of Chebyshev polynomials of the relevant Jacobi elliptic function

Homoclinic chaos in coupled SQUIDs

An rf superconducting quantum interference device (SQUID) consists of a superconducting ring interrupted by a Josephson junction (JJ). The induced supercurrents around the ring are determined by the JJ through the celebrated Josephson relations. We study the dynamics of a pair of parametrically-driven coupled SQUIDs lying on the same plane with their axes in parallel. The drive is through the alternating critical current of the JJs. This system exhibits rich nonlinear behavior, including chaotic effects. We take advantage of the weak damping that characterizes these systems to perform a multiple-scales analysis and obtain amplitude equations, describing the slow dynamics of the system. This picture allows us to expose the existence of homoclinic orbits in the dynamics of the integrable part of the slow equations of motion. Using high-dimensional Melnikov theory, we are able to obtain explicit parameter values for which these orbits persist in the full system, consisting of both Hamiltonian and non-Hamiltonian perturbations, to form so called Shilnikov orbits, indicating a loss of integrability and the existence of chaos

Stability of localized structures in generalized DNLS equations near the anti-continuum limit

In this work we consider the stability of localized structures in discrete nonlinear Schrödinger lattices with generalized nonlinearities, depending on the absolute value of the field. We illustrate how the continuation of solutions in one-, as well as higher dimensions proceeds from the anti-continuum limit and show how to generalize the results of Pelinovsky et al (2005 Physica D 212 1) for arbitrary nonlinearities. As a case example of particular experimental relevance, we showcase our main findings in the special setting of the lattice with the saturable (photorefractive) nonlinearity in one and two dimensions. Our analytical results are found to be in good agreement with direct numerical computations

Stability of localized structures in generalized DNLS equations near the anti-continuum limit

In this work we consider the stability of localized structures in discrete nonlinear Schrödinger lattices with generalized nonlinearities, depending on the absolute value of the field. We illustrate how the continuation of solutions in one-, as well as higher dimensions proceeds from the anti-continuum limit and show how to generalize the results of Pelinovsky et al (2005 Physica D 212 1) for arbitrary nonlinearities. As a case example of particular experimental relevance, we showcase our main findings in the special setting of the lattice with the saturable (photorefractive) nonlinearity in one and two dimensions. Our analytical results are found to be in good agreement with direct numerical computations

Bifurcation Results for Traveling Waves in Nonlinear Magnetic Metamaterials

In this work, we study a model of a one-dimensional magnetic metamaterial formed by a discrete array of nonlinear resonators. We focus on periodic and localized traveling waves of the model, in the presence of loss and an external drive. Employing a Melnikov analysis we study the existence and persistence of such traveling waves, and study their linear stability. We show that, under certain conditions, the presence of dissipation and/or driving may stabilize or destabilize the solutions. Our analytical results are found to be in good agreement with direct numerical computations. </jats:p

Travelling waves in nonlinear magneto-inductive lattices

We consider a lattice equation modelling one-dimensional metamaterials formed by a discrete array of nonlinear resonators. We focus on periodic travelling waves due to the presence of a periodic force. The existence and uniqueness results of periodic travelling waves of the system are presented. Our analytical results are found to be in good agreement with direct numerical computations