"Discrete Breathers in One-Dimensional Diatomic Granular Crystals"

A new paper by my collaborators and me has just appeared in Physical Review Letters. This is my 4th paper in PRL. The concerns discrete breathers in granular crystal, and it includes theory, numerical simulations, and (especially!) experiments. In fact, this paper gives the first experimental demonstration of intrinsic localized modes (these are the discrete breathers) in granular crystals, which is a rather exciting result. I believe that Caltech is going to be issuing a press release, so I'll pass along that and any ensuing press coverage later.

Title: Discrete Breathers in One-Dimensional Diatomic Granular Crystals

Authors: N. Boechler, G. Theocharis, S. Job, P. G. Kevrekidis, Mason A. Porter, and C. Daraio

Abstract: We report the experimental observation of modulational instability and discrete breathers in a one-dimensional diatomic granular crystal composed of compressed elastic beads that interact via Hertzian contact. We first characterize their effective linear spectrum both theoretically and experimentally. We then illustrate theoretically and numerically the modulational instability of the lower edge of the optical band. This leads to the dynamical formation of long-lived breather structures, whose families of solutions we compute throughout the linear spectral gap. Finally, we experimentally observe the manifestation of the modulational instability and the resulting generation of localized breathing modes with quantitative characteristics that agree with our numerical results.