Dynamical nuclear spin polarization and the Zamboni effect in gated double quantum dots

A dynamical nuclear polarization scheme is studied in gated double dots. We demonstrate that a small polarization (similar to 0.5%) is sufficient to enhance the singlet decay time by two orders of magnitude. This enhancement is attributed to an equilibration process between the nuclear reservoirs in the two dots accompanied by reduced fluctuations in the Overhauser fields that are mediated by the electron-nuclear spin hyperfine interaction.