Nonlinear electron dynamics in a rippled channel with time-dependent electric field: Quantum Arnol'd diffusion

TL;DR

This paper investigates quantum electron diffusion in a rippled 2D waveguide under a time-periodic electric field, revealing conditions for quantum Arnol'd diffusion, its suppression by localization, and potential observability in semi-metal channels.

Contribution

It demonstrates the possibility of quantum Arnol'd diffusion in rippled channels and analyzes the effects of quantum coherence and localization on this diffusion process.

Findings

Quantum diffusion occurs only with strong enough perturbation.

Quantum diffusion rate is lower than classical due to coherence effects.

Dynamical localization can suppress quantum diffusion, similar to Anderson localization.

Abstract

We study the electron dynamics in a 2D waveguide bounded by a periodically rippled surface in the presence of the time-periodic electric field. The main attention is paid to a possibility of a weak quantum diffusion along the coupling resonance, that can be associated with the classical Arnol'd diffusion. It was found that quantum diffusion is possible only when the perturbation is large enough in order to mix many near-separatrix levels. The rate of the quantum diffusion turns out to be less than the corresponding classical one, thus indicating the influence of quantum coherent effects. Another important effect is the dynamical localization of the quantum diffusion, that may be compared with the famous Anderson localization occurring in 1D random potentials. Our estimates show that the quantum Arnol'd diffusion can be observed in semi-metal rippled channels, for which the scattering and decoherence times are larger than the saturation time due to the dynamical localization.