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Control and Detection of Singlet-Triplet Mixing in a Random Nuclear Field

F. H. L. Koppens·J. A. Folk·J. M. Elzerman·R. Hanson·L. H. Willems van Beveren·I. T. Vink·H. P. Tranitz·W. Wegscheider·L. P. Kouwenhoven·L. M. K. Vandersypen
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Abstract

We observe mixing between two-electron singlet and triplet states in a double quantum dot, caused by interactions with nuclear spins in the host semiconductor. This mixing is suppressed by applying a small magnetic field, or by increasing the interdot tunnel coupling and thereby the singlet-triplet splitting. Electron transport involving transitions between triplets and singlets in turn polarizes the nuclei, resulting in striking bistabilities. We extract from the fluctuating nuclear field a limitation on the time-averaged spin coherence time T2* of 25 ns. Control of the electron-nuclear interaction will therefore be crucial for the coherent manipulation of individual electron spins.

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F. H. L. Koppens, J. A. Folk, J. M. Elzerman, R. Hanson, L. H. Willems van Beveren, I. T. Vink, H. P. Tranitz, W. Wegscheider, L. P. Kouwenhoven, L. M. K. Vandersypen. 2005-09-02. Control and Detection of Singlet-Triplet Mixing in a Random Nuclear Field. https://doi.org/10.1126/science.1113719

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