  In this work, we present a quantum transport model for the selectivity filter
in the KcsA potassium ion channel. This model is fully consistent with the fact
that two conduction pathways are involved in the translocation of ions thorough
the filter, and we show that the presence of a second path may actually bring
advantages for the filter as a result of quantum interference. To highlight
interferences and resonances in the model, we consider the selectivity filter
to be driven by a controlled time-dependent external field which changes the
free energy scenario and consequently the conduction of the ions. In
particular, we demonstrate that the two-pathway conduction mechanism is more
advantageous for the filter when dephasing in the transient configurations is
lower than in the main configurations. As a matter of fact, K$^+$ ions in the
main configurations are highly coordinated by oxygen atoms of the filter
backbone and this increases noise. Moreover, we also show that, for a wide
range of dephasing rates and driving frequencies, the two-pathway conduction
used by the filter leads indeed to higher ionic currents when compared with the
single path model.
