Letter | Published:

Enhancement and sign change of magnetic correlations in a driven quantum many-body system

Nature volume 553, pages 481485 (25 January 2018) | Download Citation

Abstract

Periodic driving can be used to control the properties of a many-body state coherently and to realize phases that are not accessible in static systems. For example, exposing materials to intense laser pulses makes it possible to induce metal–insulator transitions, to control magnetic order and to generate transient superconducting behaviour well above the static transition temperature1,2,3,4,5,6. However, pinning down the mechanisms underlying these phenomena is often difficult because the response of a material to irradiation is governed by complex, many-body dynamics. For static systems, extensive calculations have been performed to explain phenomena such as high-temperature superconductivity7. Theoretical analyses of driven many-body Hamiltonians are more challenging, but approaches have now been developed, motivated by recent observations8,9,10. Here we report an experimental quantum simulation in a periodically modulated hexagonal lattice and show that antiferromagnetic correlations in a fermionic many-body system can be reduced, enhanced or even switched to ferromagnetic correlations (sign reversal). We demonstrate that the description of the many-body system using an effective Floquet–Hamiltonian with a renormalized tunnelling energy remains valid in the high-frequency regime by comparing the results to measurements in an equivalent static lattice. For near-resonant driving, the enhancement and sign reversal of correlations is explained by a microscopic model of the system in which the particle tunnelling and magnetic exchange energies can be controlled independently. In combination with the observed sufficiently long lifetimes of the correlations in this system, periodic driving thus provides an alternative way of investigating unconventional pairing in strongly correlated systems experimentally7,9,10.

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Acknowledgements

We thank D. Abanin, D. Greif, D. Jaksch, M. Landini, Y. Murakami, N. Tsuji, P. Werner and W. Zwerger for discussions. We acknowledge SNF (Project Number 200020_169320 and NCCR-QSIT), Swiss State Secretary for Education, Research and Innovation Contract No. 15.0019 (QUIC) and ERC advanced grant TransQ (Project Number 742579) for funding.

Author information

Affiliations

  1. Institute for Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland

    • Frederik Görg
    • , Michael Messer
    • , Kilian Sandholzer
    • , Gregor Jotzu
    • , Rémi Desbuquois
    •  & Tilman Esslinger
  2. Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany

    • Gregor Jotzu

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Contributions

All authors contributed extensively to the work presented in this manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Tilman Esslinger.

Reviewer Information Nature thanks J. Freericks and D. Huse for their contribution to the peer review of this work.

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https://doi.org/10.1038/nature25135

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