Quantum computation and the production of entangled photons using coupled quantum dots

We review recent theoretical progress on the use of electron spins as qubits in coupled semiconductor quantum dots for quantum information processing. We discuss the spin exchange mechanism and its microscopic origin in both laterally and vertically tunnel-coupled quantum dots and explain how it can be used to implement the quantum XOR gate which, in combination with single spin rotations, allows to perform arbitrary quantum computations. In addition to their functionality as a quantum gate, coupled quantum dots can act as a source for photon pairs in entangled polarization states which are useful for quantum communication. We describe a mechanism for the production of such entangled photon pairs via a biexciton state in tunnel-coupled quantum dots.