Spin-based optical quantum gates via Pauli blocking in semiconductor quantum dots

We present a solid-state implementation of an all-optical spin-based quantum computer. Our proposal for a quantum-computing device is based on the spin degrees of freedom of electrons confined in semiconductor quantum dots, thus benefitting from relatively long coherence times. Combining Pauli blocking effects with properly tailored ultrafast laser pulses, we obtain sub-picosecond spin-dependent switching of the Coulomb interaction, which is the essence of our gating operations. This allows us to realize fast quantum gates which do not translate into fast decoherence times and pave the way for an all-optical spin-based quantum computer.