@article{boscain2012weak,
  title={A weak spectral condition for the controllability of the bilinear Schr{\"o}dinger equation with application to the control of a rotating planar molecule},
  author={Boscain, Ugo and Caponigro, Marco and Chambrion, Thomas and Sigalotti, Mario},
  journal={Communications in Mathematical Physics},
  volume={311},
  number={2},
  pages={423--455},
  year={2012},
  publisher={Springer}
}