The stochastic web concept dates back to the 1960s when Arnold showed (Arnold,1964) that, in non-degenerate Hamiltonian systems of dimension exceeding 2, reso-nance lines necessarily intersect, forming an infinite-sized web in the Poincar6 sec-tion. It provides in turn for a slow chaotic (sometimes called "stochastic") diffusionfor infinite distances in relevant dynamical variables.
It was discovered towards the end of 1980s (Zaslavsky et al., 1986; Chernikovet al., 1987a,b, 1988) that, in degenerate or nearly-degenerate systems, a stochas-tic web may arise even if the dimension is 3/2. One of the archetypal examples ofsuch a low-dimensional stochastic web arises in the 1D harmonic oscillator per-turbed by a weak traveling wave the frequency of which coincides with a multipleof the natural frequency of the oscillator (Zaslavsky, 2007; Chernikov et al., 1987b;Zaslavsky et al., 1991). Perturbation plays a dual role: on the one hand, it givesrise to a slow dynamics characterized by an auxiliary Hamiltonian that possesses aninfinite web-like separatrix; on the other hand, the perturbation destroys this self-generated separatrix, replacing it by a thin chaotic layer. Such a low-dimensionalstochastic web may be relevant to a variety of physical systems and plays an impor-tant role in corresponding transport phenomena: see (Zaslavsky, 2007; Chernikovet al., 1987b; Zaslavsky et al., 1991) for reviews on relevant classical systems. Inaddition, there are quantum systems in which the dynamics of transport reduces tothat in the classical model described above. The latter concerns e.g. nanometre-scalesemiconductor superlattices with an applied voltage and magnetic fied (Fromholdet al., 2001, 2004).