Entropic stochastic resonance enables trapping under periodic confinement: a Brownian-dynamics study.

Entropically mediated phenomena are of emerging interest as a driving force for microscale and nanoscale transport, but their underlying stochastic nature makes them challenging to rationally manipulate and control. Stochastic resonance offers an intriguing avenue to overcome these difficulties by establishing a clear connection between the system response (the output) and an externally imposed driving force (the input). Previous studies have generally adopted a signal-processing viewpoint to classify the output in terms of a signal-to-noise ratio, but this link does not convey information that is immediately useful to infer parameters relevant to transport. Here we address this issue by applying Brownian-dynamics simulations to elucidate the residence time distribution encountered by a particle as it travels through a channel incorporating periodic constrictions. A sinusoidal longitudinal driving force is applied with a superimposed continuous orthogonal component, making it possible to identify frequency and amplitude conditions where temporal coherence with the particle's motion can be achieved. This resonant state reflects a synergistic combination of geometry and driving force that can be exploited to confine species at discrete locations, offering possibilities for directed manipulation.