Slime mould logical gates: exploring ballistic approach

Plasmodium of \emph{Physarum polycephalum} is a single cell visible by unaided eye. On a non-nutrient substrate the plasmodium propagates as a traveling localization, as a compact wave-fragment of protoplasm. The plasmodium-localization travels in its originally predetermined direction for a substantial period of time even when no gradient of chemo-attractants is present. We utilize this property of \emph{Physarum} localizations to design a two-input two-output Boolean logic gates $<x, y> \to <xy, x+y>$ and $<x, y> \to <x, bar{x}y>$. We verify the designs in laboratory experiments and computer simulations. We cascade the logical gates into one-bit half-adder and simulate its functionality.