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Quantum dots

Through locks to narrows

Nature Physics volume 5, pages 710–711 (2009)Cite this article

In semiconductor quantum dots, single electron spins are surrounded by a bath of nuclear spins. Controlling the nuclear magnetization is difficult, but two experiments now demonstrate locking of the average nuclear field to a particular value and narrowing of the nuclear randomness.

Single electron spins seem to be a natural choice for applications in quantum information processing. But for them to be useful in practical systems, long coherence times and a means for their precise local coherent manipulation are needed. For electrons confined to nanometre-scale semiconductor quantum dots1, these goals remain elusive, mainly owing to their strong coupling to randomly oriented nuclear spins in the host materials. A random nuclear state acts as an unknown (and fluctuating) local magnetic field for an electron spin. If the nuclear field could be controllably polarized and thus 'locked' to a predefined value, the large local field could be used to address single spins in the frequency domain. Even more significantly, if random fluctuations in the nuclear field could be reduced — and therefore its statistical distribution narrowed — the dominant source of electron-spin decoherence would be eliminated. Writing on pages 764 and 758 of this issue, respectively, Ivo Vink et al.2 and Christian Latta et al.3, report independent studies with distinctly different experimental set-ups, in which they achieved both locking and narrowing of the nuclear field.

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Figure 1: Dynamic nuclear-polarization mechanisms and detection techniques.

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Authors and Affiliations

  1. William A. Coish is at the Institute for Quantum Computing and in the Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. wcoish@iqc.ca,

    William A. Coish

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  1. William A. Coish
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Coish, W. Through locks to narrows. Nature Phys 5, 710–711 (2009). https://doi.org/10.1038/nphys1414

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  • DOI: https://doi.org/10.1038/nphys1414

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