Observing ballistic transport beyond the mean free time.

Characteristics of ballistic motion are observable in transport experiments when the associated time scale is shorter than the impurity scattering time. We point out a general mechanism that circumvents this rule by linking different time scales through phase space volume conservation, a fundamental property of Hamiltonian systems. This finding was inspired by recent experiments on graphene antidot lattices, which show ballistic transport effects despite strong impurity scattering. We therefore exemplify this general mechanism for electronic transport in antidot superlattices and explain magnetoresistance experiments in graphene samples.