Universal power law decay of spin polarization in double quantum dot

We study the spin dynamics and spin noise in a double quantum dot, taking into account the interplay between hopping, exchange interaction, and the hyperfine interaction. At short timescales the spin relaxation is governed by the spin dephasing in the random nuclear fields. At long timescales the spin polarization obeys universal power law $1/t$ independent of the relation between all the parameters of the system. This effect is caused by the competition between the spin blockade effect and the hyperfine interaction. The spin noise spectrum of the system universally diverges as $ln(1/\ensuremath{\omega})$ at low frequencies.