  Self propelled particle (SPP) models are often compared with animal swarms.
However, the collective behaviour observed in experiments usually leaves
considerable unconstrained freedom in the structure of these models. To tackle
this degeneracy, and better distinguish between candidate models, we study
swarms of SPPs circulating in channels (like spins) where we permit information
to pass through windows between neighbouring channels. Co-alignment between
particles then couples the channels (antiferromagnetically) so that they tend
to counter-rotate. We study channels arranged to mimic a geometrically
frustrated antiferromagnet and show how the effects of this frustration allow
us to better distinguish between SPP models. Similar experiments could
therefore improve our understanding of collective motion in animals. Finally we
discuss how the spin analogy can be exploited to construct universal logic
gates and therefore swarming systems that can function as Turing machines.
