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Hole spin relaxation in Ge–Si core–shell nanowire qubits

Nature Nanotechnology volume 7, pages 47–50 (2012)Cite this article

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Abstract

Controlling decoherence is the biggest challenge in efforts to develop quantum information hardware1,2,3. Single electron spins in gallium arsenide are a leading candidate among implementations of solid-state quantum bits, but their strong coupling to nuclear spins produces high decoherence rates4,5,6. Group IV semiconductors, on the other hand, have relatively low nuclear spin densities, making them an attractive platform for spin quantum bits. However, device fabrication remains a challenge, particularly with respect to the control of materials and interfaces7. Here, we demonstrate state preparation, pulsed gate control and charge-sensing spin readout of hole spins confined in a Ge–Si core–shell nanowire. With fast gating, we measure T1 spin relaxation times of up to 0.6 ms in coupled quantum dots at zero magnetic field. Relaxation time increases as the magnetic field is reduced, which is consistent with a spin–orbit mechanism that is usually masked by hyperfine contributions.

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Figure 1: Spin qubit device based on a Ge–Si heterostructure nanowire.
Figure 2: Zeeman splitting of confined holes in a single quantum dot.
Figure 3: Hole-spin doublets in a Ge–Si double dot.
Figure 4: Pulsed gate measurements of spin relaxation times.

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Acknowledgements

The authors thank H. Churchill, J. Medford and E. Rashba for technical help and discussions, and acknowledge support from the DARPA/QuEST programme.

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Author notes

  1. Yongjie Hu

    Present address: Present address: Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA,

Authors and Affiliations

  1. Department of Chemistry and Chemical Biology, Harvard University, Cambridge, 02138, Massachusetts, USA

    Yongjie Hu & Charles M. Lieber

  2. Department of Physics, Harvard University, Cambridge, 02138, Massachusetts, USA

    Yongjie Hu, Ferdinand Kuemmeth & Charles M. Marcus

  3. School of Engineering and Applied Sciences, Harvard University, Cambridge, 02138, Massachusetts, USA

    Charles M. Lieber

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  1. Yongjie Hu
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  2. Ferdinand Kuemmeth
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  3. Charles M. Lieber
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  4. Charles M. Marcus
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Contributions

Y.H. and F.K. performed the experiments. Y.H. prepared the materials and fabricated the devices. Y.H., F.K., C.M.L. and C.M.M. analysed the data and co-wrote the paper. All authors discussed the results and commented on the manuscript.

Corresponding authors

Correspondence to Charles M. Lieber or Charles M. Marcus.

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The authors declare no competing financial interests.

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Hu, Y., Kuemmeth, F., Lieber, C. et al. Hole spin relaxation in Ge–Si core–shell nanowire qubits. Nature Nanotech 7, 47–50 (2012). https://doi.org/10.1038/nnano.2011.234

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