Abstract
We polarize nuclear spins in a GaAs double quantum dot by controlling two-electron spin states near the anticrossing of the singlet () and triplet () using pulsed gates. An initialized state is cyclically brought into resonance with the state, where hyperfine fields drive rapid rotations between and , “flipping” an electron spin and “flopping” a nuclear spin. The resulting Overhauser field approaches 80 mT, in agreement with a simple rate-equation model. A self-limiting pulse sequence is developed that allows the steady-state nuclear polarization to be set using a gate voltage.
- Received 6 September 2007
DOI:https://doi.org/10.1103/PhysRevLett.100.067601
©2008 American Physical Society