@misc{maassen2005purification,
  title={Purification of quantum trajectories},
  author={Hans Maassen and Burkhard Kümmerer},
  year={2005},
  eprint={quant-ph/0505084},
  archivePrefix={arXiv},
  primaryClass={quant-ph},
  url={https://arxiv.org/abs/quant-ph/0505084}
}