  We present a mechanism for quantum gates where the qubits are encoded in the
population distribution of two component ultracold atoms trapped in a
species-selective triple-well potential. The gate operation is a specific
application of a new design for an atomtronics transistor where inter-species
interaction is used to control transport, and can be realized with either
individual atoms or aggregates like Bose-Einstein condensates (BEC). We
demonstrate the operational principle with a static external potential, and
show feasible implementation with a smooth dynamical potential.
