Nuclear spin dynamics in double quantum dots: Fixed points, transients, and intermittency

Abstract

Transport through spin-blockaded quantum dots provides a means for electrical control and detection of nuclear spin dynamics in the host material. Although such experiments have become increasingly popular in recent years, interpretation of their results in terms of the underlying nuclear spin dynamics remains challenging. Here we examine nuclear polarization dynamics within a two-polarization model that supports a wide range of nonlinear phenomena. We point out a fundamental process in which nuclear spin dynamics can be driven by electron shot noise; fast electric current fluctuations generate much slower nuclear polarization dynamics, which in turn affect electron dynamics via the Overhauser field. The resulting intermittent, extremely slow current fluctuations account for a variety of observed phenomena that were not previously understood.