@Article{khaneja03boundary,
  author = 	 {Navin Khaneja and Burkhard Luy and Steffen J. Glaser},
  title = 	 {Boundary of Quantum Evolution Under Decoherence},
  journal = 	 {Proc. Nat. Acad. Sci.},
  year = 	 {2003},
  volume = 	 {100},
  number = 	 {23},
  pages = 	 {13162--13166},
  month = 	 {Nov.}
}