Electron spins for spintronics and quantum communication in quantum dots and wires

Electron spins in nanostructures such as quantum dots and wires have promising applications for spintronics, quantum computing and quantum communication. We give a brief introduction to the quantum computing proposal using electron spins in quantum dots. A quantum dot in the Coulomb blockade regime, attached to leads and in the presence of a magnetic field is used to study single-spin effects. With an ESR source, the spin can be coherently controlled, leading to Rabi-oscillations of the dot spin. It is shown that the intrinsic single-spin decoherence time T-2 is directly accessible via a stationary charge current through the dot. In addition, we show that the quantum dot acts as an efficient spin filter, single-spin read-out device or as a spin pump. Finally, we consider mobile non-local spin entangled electrons as needed for quantum communication. We propose how to create such EPR pairs by means of Andreev tunneling at a superconductor-normal junction and discuss experimental setups in which spin entanglement and non-locality may be detected via transport measurements.