  Adiabatic techniques using multi-level systems have recently been generalised
from the optical case to settings in atom optics, solid state and even
classical electrodynamics. The most well known example of these is the so
called STIRAP process, which allows transfer of a particle between different
states with large fidelity. Here we generalise and examine this process for an
atomic centre-of-mass state with a non-trivial phase distribution and show that
even though dark state dynamics can be achieved for the atomic density, the
phase dynamics will still have to be considered as a dynamical process. In
particular we show that the combination of adiabatic and non-adiabatic
behaviour can be used to engineer phase superposition states.
