@article{quantuminspiredclassicalalgorithmsfor,
  title = {Quantum principal component analysis only achieves an exponential speedup because of its state preparation assumptions},
  author = {Ewin Tang},
  year = {2018},
  eprint = {1811.00414},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/1811.00414v3},
}