Directed motion of an atomic scale engine and stability analysis

Atomic scale engines have received increasing research interests due to recent advances in nano-particle manipulation techniques. We study the model of an artificial atomic scale engine proposed by, and show numerically that the model exhibits directed motion under asymmetric particle coupling. We then conduct stability analysis of a 3-particle engine and prove that stable and unstable equilibrium points arise in an alternating sequence thus step motion can be deduced. Our analytic understanding of the complex nonlinear dynamics may guide future design of such an envisioned engine at the atomic scale.