Isolated Heisenberg magnet as a quantum time crystal

@article{Medenjak2019IsolatedHM,
  title={Isolated Heisenberg magnet as a quantum time crystal},
  author={Marko Medenjak and Berislav Bu{\vc}a and Dieter Jaksch},
  journal={Physical Review B},
  year={2019}
}
Local observables of closed many-body quantum systems are generally believed to quickly equilibrate after a quench, according to the eigenstate thermalization hypothesis. Here, the authors show that the paradigmatic Heisenberg quantum magnet violates this fundamental assumption. They analytically find measurable local correlation functions that show perpetual oscillations, while at the same time all single-particle observables equilibrate. They link their existence to the presence of dynamical… 

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