Self-polarization and dynamical cooling of nuclear spins in double quantum dots

Phys Rev Lett. 2007 Jul 20;99(3):036602. doi: 10.1103/PhysRevLett.99.036602. Epub 2007 Jul 19.


The spin-blockade regime of double quantum dots features coupled dynamics of electron and nuclear spins resulting from the hyperfine interaction. We explain observed nuclear self-polarization via a mechanism based on feedback of the Overhauser shift on electron energy levels, and propose to use the instability toward self-polarization as a vehicle for controlling the nuclear spin distribution. In the dynamics induced by a properly chosen time-dependent magnetic field, nuclear spin fluctuations can be suppressed significantly below the thermal level.