Letter | Published:

Spin–orbit-coupled fermions in an optical lattice clock

Nature volume 542, pages 6670 (02 February 2017) | Download Citation

Abstract

Engineered spin–orbit coupling (SOC) in cold-atom systems can enable the study of new synthetic materials and complex condensed matter phenomena1,2,3,4,5,6,7,8. However, spontaneous emission in alkali-atom spin–orbit-coupled systems is hindered by heating, limiting the observation of many-body effects1,2,5 and motivating research into potential alternatives9,10,11. Here we demonstrate that spin–orbit-coupled fermions can be engineered to occur naturally in a one-dimensional optical lattice clock12. In contrast to previous SOC experiments1,2,3,4,5,6,7,8,9,10,11, here the SOC is both generated and probed using a direct ultra-narrow optical clock transition between two electronic orbital states in 87Sr atoms. We use clock spectroscopy to prepare lattice band populations, internal electronic states and quasi-momenta, and to produce spin–orbit-coupled dynamics. The exceptionally long lifetime of the excited clock state (160 seconds) eliminates decoherence and atom loss from spontaneous emission at all relevant experimental timescales, allowing subsequent momentum- and spin-resolved in situ probing of the SOC band structure and eigenstates. We use these capabilities to study Bloch oscillations, spin–momentum locking and Van Hove singularities in the transition density of states. Our results lay the groundwork for using fermionic optical lattice clocks to probe new phases of matter.

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Acknowledgements

We are grateful to N. R. Cooper for insights and discussions, and S. L. Campbell, N. Darkwah Oppong, A. Goban, R. B. Hutson, D. X. Reed, J. Robinson, L. Sonderhouse and W. Zhang for technical contributions and discussions. This research is supported by NIST, the NSF Physics Frontier Center at JILA (NSF-PFC-1125844), AFOSR-MURI, AFOSR, DARPA and ARO. S.K., M.L.W. and G.E.M. acknowledge the NRC postdoctoral fellowship programme.

Author information

Author notes

    • M. L. Wall
    •  & X. Zhang

    Present addresses: The Johns Hopkins Applied Physics Laboratory, Laurel, Maryland 20723, USA (M.L.W.); International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China (X.Z.).

    • S. Kolkowitz
    •  & S. L. Bromley

    These authors contributed equally to this work.

Affiliations

  1. JILA, NIST and University of Colorado, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA

    • S. Kolkowitz
    • , S. L. Bromley
    • , T. Bothwell
    • , M. L. Wall
    • , G. E. Marti
    • , A. P. Koller
    • , X. Zhang
    • , A. M. Rey
    •  & J. Ye

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Contributions

S.K., S.L.B., T.B., G.E.M., X.Z. and J.Y. contributed to the experiments. M.L.W., A.P.K. and A.M.R. contributed to the development of the theoretical model. All authors discussed the results, contributed to the data analysis and worked together on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to S. Kolkowitz or S. L. Bromley.

Reviewer Information

Nature thanks L. Duan and the other anonymous reviewer(s) for their contribution to the peer review of this work.

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DOI

https://doi.org/10.1038/nature20811

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