Transport of active spinning particles in porous media

Transport of active particles in confinement is of interest in multiple fields from biology to synthetic systems. Here, we explore how spinning particles behave in porous media and in particular how their transport is affected by the local structure of the medium. We demonstrate that spinning particles within a liquid in a 2D ordered array of posts display non-equilibrium states of ballistic transport. We further show that such states occur in the limit of small Reynolds number and high Peclet number. The origin of these states is found in the opening of a “directionality gap” in the density of states due to the breaking of rotational symmetry. Furthermore, we also show that these states are not affected by a large quantity of defects or disorder on the lattice, which resemble edge currents in topological insulators. Our results may be important in understanding transport of active mater in confined or (un)structured environments.