@misc{indiciae164b95ceb29a,
  title = {Time operators and time crystals: self-adjointness by topology change},
  author = {Nakatsugawa, Keiji and Fujii, T. and Saxena, Avadh and Tanda, Satoshi},
  year = {2019},
  doi = {10.1088/1751-8121/ab3f46},
  url = {https://www.osti.gov/biblio/1699452},
  note = {Source identifier: 1699452}
}