Letter

Observation of a discrete time crystal

Received:
Accepted:
Published online:

Abstract

Spontaneous symmetry breaking is a fundamental concept in many areas of physics, including cosmology, particle physics and condensed matter1. An example is the breaking of spatial translational symmetry, which underlies the formation of crystals and the phase transition from liquid to solid. Using the analogy of crystals in space, the breaking of translational symmetry in time and the emergence of a ‘time crystal’ was recently proposed2,3, but was later shown to be forbidden in thermal equilibrium4,5,6. However, non-equilibrium Floquet systems, which are subject to a periodic drive, can exhibit persistent time correlations at an emergent subharmonic frequency7,8,9,10. This new phase of matter has been dubbed a ‘discrete time crystal’10. Here we present the experimental observation of a discrete time crystal, in an interacting spin chain of trapped atomic ions. We apply a periodic Hamiltonian to the system under many-body localization conditions, and observe a subharmonic temporal response that is robust to external perturbations. The observation of such a time crystal opens the door to the study of systems with long-range spatio-temporal correlations and novel phases of matter that emerge under intrinsically non-equilibrium conditions7.

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Acknowledgements

We acknowledge discussions with M. Zaletel and D. Stamper-Kurn. This work was supported by the ARO Atomic and Molecular Physics Program, the AFOSR MURI on Quantum Measurement and Verification, the IARPA LogiQ program, the IC Postdoctoral Research Fellowship Program, the NSF Physics Frontier Center at JQI (and the PFC Seed Grant), and the Miller Institute for Basic Research in Science. A.V. was supported by the AFOSR MURI grant FA9550- 14-1-0035 and the Simons Investigator Program. N.Y.Y. acknowledges support from the LDRD Program of LBNL under US DOE Contract No. DE-AC02-05CH11231.

Author information

Affiliations

  1. Joint Quantum Institute, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, Maryland 20742, USA

    • J. Zhang
    • , P. W. Hess
    • , A. Kyprianidis
    • , P. Becker
    • , A. Lee
    • , J. Smith
    • , G. Pagano
    •  & C. Monroe
  2. Department of Physics, University of California Berkeley, Berkeley, California 94720, USA

    • I.-D. Potirniche
    • , A. Vishwanath
    •  & N. Y. Yao
  3. Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA

    • A. C. Potter
  4. Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA

    • A. Vishwanath
  5. IonQ, Inc., College Park, Maryland 20742, USA

    • C. Monroe

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Contributions

J.Z., P.W.H., A.K., P.B., A.L., J.S., G.P. and C.M. all contributed to experimental design, construction, data collection and analysis. I.-D.P., A.C.P., A.V. and N.Y.Y. all contributed to the theory for the experiment. All work was performed under the guidance of N.Y.Y. and C.M. All authors contributed to this manuscript.

Competing interests

C.M. is a founding scientist of ionQ, Inc.

Corresponding author

Correspondence to J. Zhang.

Reviewer Information Nature thanks H. Haeffner and the other anonymous reviewer(s) for their contribution to the peer review of this work.

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