  We consider a three-node fully connected network (Delta network) showing that
a coherent population trapping phenomenon occurs, generalizing results for the
Lambda network known to support a dark state. Transport in such structures
provides signatures of detrapping, which can be triggered by external controls.
In the presence of an environment it turns out to be sensitive to its
Markovianity. Adiabatic modulation of the system's parameters may yield
coherent population transfer, analogous to the stimulated Raman adiabatic
passage phenomenon. Robustness of this protocol against non-adiabatic
transitions is studied. Coherent nanostructures where these phenomena are
relevant for quantum transport and quantum protocols are suggested.
