@article{oai:repo.qst.go.jp:00048631,
 author = {Choi, Soonwon and Choi, Joonhee and Landig, Renate and Kucsko, Georg and Zhou, Hengyun and Isoya, Junichi and Jelezko, Fedor and Onoda, Shinobu and Sumiya, Hitoshi and Khemani, Vedika and von, Keyserlingk Curt and Y., Yao Norman and Demler, Eugene and D., Lukin Mikhail and 小野田 忍},
 journal = {Nature},
 month = {Mar},
 note = {Understanding quantum dynamics away from equilibrium is an outstanding challenge in the modern physical sciences. Out of equilibrium systems can display a rich variety of phenomena, including self-organized synchronization and dynamical phase transitions. More recently, advances in the controlled manipulation of isolated many-body systems have enabled detailed studies of non-equilibrium phases in strongly interacting quantum matter; for example, the interplay between periodic driving, disorder and strong interactions has been predicted to result in exotic ‘time-crystalline’ phases, in which a system exhibits
temporal correlations at integer multiples of the fundamental driving period, breaking the discrete time-translational symmetry of the underlying drive. Here we report the experimental observation of such discrete time-crystalline order in a driven, disordered ensemble of about one million dipolar spin impurities in
diamond at room temperature. We observe long-lived temporal correlations, experimentally identify the phase boundary and find that the temporal order is protected by strong interactions. This order is remarkably stable to perturbations, even in the presence of slow thermalization. Our work opens the door to exploring dynamical phases of matter and controlling interacting, disordered
many-body systems.},
 pages = {221--225},
 title = {Observation of discrete time-crystalline order in a disordered dipolar many-body system},
 volume = {543},
 year = {2017}
}