  Inducing transport in electrolyte-filled nanopores with dc fields has led to
influential applications ranging from nanosensors to DNA sequencing. Here we
use the Poisson-Nernst-Planck and Navier-Stokes equations to show that unbiased
ac fields can induce comparable directional flows in gated conical nanopores.
This flow exclusively occurs at intermediate driving frequencies and hinges on
the resonance of two competing timescales, representing space charge
development at the ends and in the interior of the pore. We summarize the
physics of resonant nanopumping in an analytical model that reproduces the
results of numerical simulations. Our findings provide a generic route towards
real-time controllable flow patterns, which might find applications in
controlling the translocation of particles such as small molecules or
nanocolloids.
