Portal de Periódicos da CAPES

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

2005; American Association for the Advancement of Science; Volume: 309; Issue: 5739 Linguagem: Inglês

10.1126/science.1113719

1095-9203

Frank H. L. Koppens, Joshua Folk, J. M. Elzerman, Ronald Hanson, L. H. Willems van Beveren, I. T. Vink, H.-P. Tranitz, W. Wegscheider, Leo P. Kouwenhoven, L. M. K. Vandersypen,

Advancements in Semiconductor Devices and Circuit Design

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.