RESUMO
We study the propagation of waves in quasi-one-dimensional finite periodic systems whose classical (ray) dynamics is diffusive. By considering a random matrix model for a chain of L identical chaotic cavities, we show that its average conductance as a function of L displays an ohmic behavior even though the system has no disorder. This behavior, with an average conductance decay N/L, where N is the number of propagating modes in the leads that connect the cavities, holds for 1âªLâ²âN. After this regime, the average conductance saturates at a value of O(âN) given by the average number of propagating Bloch modes
RESUMO
We study the number of propagating Bloch modes N(B) of an infinite periodic billiard chain. The asymptotic semiclassical behavior of this quantity depends on the phase-space dynamics of the unit cell, growing linearly with the wave number k in systems with a non-null measure of ballistic trajectories and going like â¼square root of k in diffusive systems. We have calculated numerically N(B) for a waveguide with cosine-shaped walls exhibiting strongly diffusive dynamics. The semiclassical prediction for diffusive systems is verified to good accuracy and a connection between this result and the universality of the parametric variation of energy levels is presented.