Quantum and classical superballistic transport in a relativistic kicked-rotor system.

As an unusual type of anomalous diffusion behavior, (transient) superballistic transport is not well known but has been experimentally simulated recently. Quantum superballistic transport models to date are mainly based on connected sublattices which are constructed to have different properties. In this work, we show that both quantum and classical superballistic transport in the momentum space can occur in a simple periodically driven Hamiltonian system, namely, a relativistic kicked-rotor system with a nonzero mass term. The nonzero mass term essentially realizes a situation, now in the momentum space, in which two (momentum) sublattices with different dispersion relations (and hence different nature of on-site potential) are connected as a junction. It is further shown that the quantum and classical superballistic transport should occur under much different choices of the system parameters. The results are of interest to studies of anomalous transport, quantum and classical chaos, and the issue of quantum-classical correspondence.