Theoretical Study on Electron Spin Dynamics in Semiconductor Nanostructures

我们investigated theoretically the electron spin relaxation rate in a single quantum disk andclarified its dependence on the magnetic field strengththe temperature and the strength of quantum confinement. In the weak confinement regime，the spin relaxation rate at low temperatures is dominated by the two-phonon processes and itsdependence on the magnetic field is rather weak. In the strong confinement regimeon the other hand，the spin relaxation rate at low temperatures is governed by the one phonon processes and exhibitsthe characteristic fourth power dependence on the magnetic field at moderately strong field range.however,it is predicted that a crossover occurs in the relative weight between the phonon and thetwo-phonon processes around a few Tesla and the spin relaxation rate at low magnetic fields isdetermined by the two phonon processes.We已投资the quantum dynamics of theelectron nuclei coupled system in a double quantum dot and discovered a couple of new phenomena与核辐射系统的quantum性质相关。the bunching of results of the electron spin measurements and the revival in the conditional可能性是salient features of quantum dynamics. The underlying mechanism is The squeezing ofnuclear spin state through the electron spin measurements. This squeezing is expected to leadto the elongation of the electron spin coherence time。

We investigated theoretically the electron spin relaxation rate in a single quantum disk and clarified its dependence on the magnetic field strength, the temperature and the strength of quantum confinement. In the weak confinement regime, the spin relaxation rate at low temperatures is dominated by the two-phonon processes and its dependence on the magnetic field is rather weak. In the strong confinement regime, on the other hand, the spin relaxation rate at low temperatures is governed by the one・phonon processes and exhibits the characteristic fourth power dependence on the magnetic field at moderately strong field range. However, it is predicted that a crossover occurs in the relative weight between the one・phonon and the two-phonon processes around a few Tesla and the spin relaxation rate at low magnetic fields is determined by the two・phonon processes.We have investigated the quantum dynamics of the electron・nuclei coupled system in a double quantum dot and discovered a couple of new phenomena related to the quantum nature of nuclear spin system. Especially, the bunching of results of the electron spin measurements and the revival in the conditional probabilities are salient features of quantum dynamics. The underlying mechanism is the squeezing of the nuclear spin state through the electron spin measurements. This squeezing is expected to lead to the elongation of the electron spin coherence time.