  By analysis and simulation we demonstrate two methods for achieving complete
orientational alignment of a set of identical, asymmetric colloidal objects
dispersed randomly in a fluid. Sedimentation or electrophoresis in a constant
field can lead to partial alignment, in which the objects rotate about a common
body axis, but the phases of rotation for these objects are random. We show
that this phase disorder can be removed by two forms of programmed forcing.
First, simply alternating the forcing between two directions reduces the
statistical entropy of the orientation arbitrarily. Second, addition of a small
rotating component to the applied field in analogy to magnetic resonance can
lead to phase locking of the objects' orientation. We identify conditions for
alignment of a broad class of generic objects and discuss practical
limitations.
