Inhomogeneous nuclear spin flips: Feedback mechanism between electronic states in a double quantum dot and the underlying nuclear spin bath

We discuss a feedback mechanism between electronic states in a two-electron double quantum dot and the underlying nuclear spin bath. We analyze two pumping cycles for which this feedback provides a force for the Overhauser fields of the two dots to either equilibrate or diverge. Which of these effects is favored depends on the g factor and Overhauser coupling constant of the material. The strength of the effect increases with the ratio of Overhauser coupling to electron exchange energy and also increases as the external magnetic field decreases. ©2010 The American Physical Society