Multiple Nuclear Polarization States in a Double Quantum Dot

We observe multiple stable states of nuclear polarization and nuclear self-tuning over a large range of fields in a double quantum dot under conditions of electron spin resonance. The observations can be understood within an elaborated theoretical rate equation model for the polarization in each of the dots, in the limit of strong driving. This model also captures unusual features of the data, such as fast switching and a ‘‘wrong’’ sign of polarization. The results reported enable applications of this polarization effect, including accurate manipulation and control of nuclear fields