  We demonstrate transport rectification in a hermitian Hamiltonian quantum
ratchet by a dissipative, dynamic impurity. While the bulk of the ratchet
supports transport in both directions, the properly designed loss function of
the local impurity acts as a direction-dependent filter for the moving states.
We analyse this scheme theoretically by making use of Floquet-S-Matrix theory.
In addition, we provide the direct experimental observation of one-way
transmittance in periodically modulated plasmonic waveguide arrays containing a
local impurity with engineered losses.
