  The purpose of the paper is to point out some typos and to observe that the
main result of V. Ramakrishna, K. Flores, H. Rabitz and R. J. Ober, Phys. Rev.
A Volume 62, 054309, 2000 remains valid (and this validity can be verified in a
constructive fashion) with only the requirement that the su(2) matrices A and B
in the paper in the title be linearly independent. An interpretation of this
constructive extension, in terms of Givens rotations of real Euclidean space,
is given.
