  We explore protocols for three-state adiabatic passage where the tunnel
matrix elements are varied digitally, rather than smoothly as is the case with
conventional adiabatic passage. In particular, we focus on the STIRAP and
related three-state schemes where the control is applied stepwise, with either
equal spaced levels for the tunnel matrix elements or uniform pulse lengths.
Our results show that the evolution typically shows the hallmarks of
conventional adiabatic passage, although with additional resonances exhibiting
no state transfer.
