  Molecular separation traditionnally relies on sieving processes across
passive nanoporous membranes. Here we explore theoretically the concept of
non-equilibrium active sieving. We investigate a simple model for an active
noisy nanopore, where gating - in terms of size or charge - is externally
driven at a tunable frequency. Our analytical and numerical results unveil a
rich sieving diagram in terms of the forced gating frequency. Unexpectedly, the
separation ability is strongly increased as compared to its passive (zero
frequency) counterpart. It points also to the possibility of tuning dynamically
the osmotic pressure. Active separation outperforms passive sieving and
represents a promising avenue for advanced filtration.
