2005/09/02 by F. H. L. Koppens, J. A. Folk, J. M. Elzerman +7 · 1 citation
Physics and Astronomy · #cond-mat.mes-hall
paper · pdf · doi:10.1126/science.1113719
published as Science vol 309 p.1346 (2005) · 4 pages main text, 4 figures
arxiv created 2005/09/02 · arxiv updated 2009/12/01
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.