  In their Letter [A. Tanaka and M. Miyamoto, Phys. Rev. Lett. 98, 160407
(2007)], Tanaka and Miyamoto introduce a kicked spin model, for which they
point out the generic existence of exotic eigenvalue anholonomy. They proceed
to show the potential utility of the model for quantum state manipulation and
quantum information processing. While we believe their model to be vary useful
and their argument to be revealing, In our view, there are three missing
elements in the article, without which their discussion seems to be incomplete
and the prospect of the application limited. They are on dynamical phase, gauge
potential, and on adiabaticity.
