Spin and charge dynamics in semiconductor quantum dots.

摘要

In this dissertation, we present detailed studies on the nuclear spin dynamics and relaxation, electron spin decoherence, and non-equilibrium electronic transport in Kondo regime for semiconductor quantum dots. We calculate the coefficients of nuclear spin diffusion with two different methods. It is shown that hyperfine interaction decreases the diffusion coefficients dramatically. We discuss the performance of the coherent spin transfer with the nuclear quantum memory using quantum dot, and calculate the operation fidelity due to nuclear spin dipolar coupling. We also study the possible nuclear spin polarization and relaxation mechanism in a spin-blocked double-dot, and qualitatively explain some of the recent experimental results. We study the electron spin decoherence time (T2) resulting from hyperfine coupling with the equation-of-motion approach. We show that the transverse electron spin undergoes a complete decay in the long time limit by including higher-order processes. Finally we develop a real-time density matrix method and apply it to study the non-equilibrium electron transport through quantum dots in the context of Kondo effect.