  We report on the onset of anti-resonant behaviour of mass transport systems
driven by time-dependent forces. Anti-resonances arise from the coupling of a
sufficiently high number of space-time modes of the force. The presence of
forces having a wide space-time spectrum, a necessary condition for the
formation of an anti-resonance, is typical of confined systems with uneven and
deformable walls that induce entropic forces dependent on space and time. We
have analyzed, in particular, the case of polymer chains confined in a flexible
channel and shown how they can be sorted and trapped. The presence of
resonance-antiresonance pairs found can be exploited to design protocols able
to engineer optimal transport processes and to manipulate the dynamics of
nano-objects.
