M. Gullans, J. J. Krich, J. M. Taylor, B. I. Halperin, M. D. Lukin
We theoretically study the dynamic polarization of lattice nuclear spins in GaAs double quantum dots containing two electrons. We introduce a semiclassical model that allows to explore a wide range of parameter regimes in this system. We identify three regimes of long-term dynamics, including the build up of a large difference in the Overhauser fields across the dots, the saturation of the nuclear polarization process associated with formation of so-called "dark states," and the elimination of the difference field. When the dots are different sizes, build up of difference fields follows the polarization process, whereas for nearly identical dots, we find the dynamics are strongly influenced by nuclear spin noise. In the absence of noise, all three steady states are achieved depending on parameters. However, with nuclear spin noise we find the build up of difference fields competes with polarization saturation in dark states, while the elimination of the difference field does not, in general, correspond to a stable steady state of the polarization process. These results are in agreement with dynamic nuclear polarization experiments in double quantum dots.
View original:
http://arxiv.org/abs/1212.6953
No comments:
Post a Comment