@article{Duval:2017,
  author  = "G. Duval and A. Maciejewski and W. Respondek",
  title   = "Non-integrability of the optimal control problem for n-level quantum systems",
  journal = "Journal of Physics A : Mathematical and Theoretical",
  volume  = "Vol. 50",
  number  = "no. 17",
  pages   = "1--27",
  year    = "2017",
}