@article{MariEisert2012,
  author    = {Andrea Mari and Jens Eisert},
  title     = {Positive wigner functions render classical simulation of quantum computation efficient},
  journal   = {Physical review letters},
  volume    = {109},
  number    = {23},
  doi       = {10.1103/PhysRevLett.109.230503},
  year      = {2012},
}