@article {khaneja01time,
    AUTHOR = {Khaneja, Navin and Glaser, Steffen J. and Brockett, Roger W.},
     TITLE = {Time Optimal Control in Spin Systems},
   JOURNAL = {Phys. Rev. A},
  FJOURNAL = {Physical Review. A.},
    VOLUME = {63},
      YEAR = {2001},
    NUMBER = {3},
     PAGES = {032308, 13}
}