Trapping and steering on lattice strings: Virtual slow waves and directional and nonpropagating excitations.

Abstract

Using a lattice string model, a number of peculiar excitation situations related to nonpropagating excitations and nonradiating sources are demonstrated. External fields can be used to trap excitations locally but also lead to the ability to steer such excitations dynamically as long as the steering is slower than the field's wave propagation. I present explicit constructions of a number of examples, including temporally limited nonpropagating excitations, directional excitation and virtually slowed propagation. Using these dynamical lattice constructions I demonstrate that neither persistent temporal oscillation nor static localization are necessary for nonpropagating excitations to occur.