Abstract

One of the key challenges in spectroscopy is the inhomogeneous broadening that masks the homogeneous spectral lineshape and the underlying coherent dynamics. Techniques such as four-wave mixing and spectral hole-burning are used in optical spectroscopy1,2,3, and spin-echo4 in nuclear magnetic resonance (NMR). However, the high-power pulses used in spin-echo and other sequences4,5,6,7,8 often create spurious dynamics7,8 obscuring the subtle spin correlations important for quantum technologies5,6,9,10,11,12,13,14,15,16,17. Here we develop NMR techniques to probe the correlation times of the fluctuations in a nuclear spin bath of individual quantum dots, using frequency-comb excitation, allowing for the homogeneous NMR lineshapes to be measured without high-power pulses. We find nuclear spin correlation times exceeding one second in self-assembled InGaAs quantum dots—four orders of magnitude longer than in strain-free III–V semiconductors. This observed freezing of the nuclear spin fluctuations suggests ways of designing quantum dot spin qubits with a well-understood, highly stable nuclear spin bath.

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Acknowledgements

The authors are grateful to K. V. Kavokin for useful discussions. This work has been supported by the EPSRC Programme Grant EP/J007544/1, ITN S3NANO. E.A.C. was supported by a University of Sheffield Vice-Chancellor’s Fellowship and a Royal Society University Research Fellowship. I.F. and D.A.R. were supported by EPSRC. Computational resources were provided in part by the University of Sheffield HPC cluster ‘Iceberg’.

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Affiliations

  1. Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK

    • A. M. Waeber
    • , A. I. Tartakovskii
    • , M. S. Skolnick
    •  & E. A. Chekhovich
  2. Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 3JD, UK

    • M. Hopkinson
  3. Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK

    • I. Farrer
    • , D. A. Ritchie
    •  & J. Nilsson
  4. Toshiba Research Europe Limited, Cambridge Research Laboratory, Cambridge CB4 0GZ, UK

    • R. M. Stevenson
    • , A. J. Bennett
    •  & A. J. Shields
  5. Department of Physics, University of Konstanz, D-78457 Konstanz, Germany

    • G. Burkard

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Contributions

M.H., I.F., D.A.R., J.N., R.M.S., A.J.B. and A.J.S. developed and grew the samples. A.M.W. and E.A.C. conceived and designed the experiments and analysed the data. A.M.W. performed the experiments. E.A.C. performed the numerical modelling. E.A.C., A.M.W., M.S.S., A.I.T., G.B. and A.J.B. wrote the manuscript with input from all authors. E.A.C. coordinated the project.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to A. M. Waeber or E. A. Chekhovich.

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https://doi.org/10.1038/nphys3686

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