Quantum Manipulation of Spins in Semiconductors

Semiconductor spintronics has the aim to develop functional devices for future information processing. We will address two fundamental aspects, which are important for the performance of novel device concepts. The first part of the project deals with the creation, control, and detection of spin-entanglement in semiconductor nano-devices. We will address the important question of dephasing of spin-entangled electrons and the detector backaction in semiconductor quantum channels caused, e.g., by spin-relaxation or electron-electron interaction. An import vision is a more general scheme to detect quantum correlations, since traditional criteria like the violation of Bell inequalities might fail in semiconductor devices. This new criteria will be based on higher order correlation functions. Secondly we will study the interaction of a spin-polarized current with a domain wall and develop quantum kinetic equations for magnetic semiconductors with non-collinear magnetization configurations. These equations will describe the coupled electron and the magnetization dynamics. We will obtain important experimentally accessible quantities like the critical current for domain wall motion or the saturation velocity.