Spin-based quantum-information processing with semiconductor quantum dots and cavity QED

A quantum-information-processing scheme is proposed with semiconductor quantum dots located in a high-$Q$ single-mode QED cavity. The spin degrees of freedom of one excess conduction electron of the quantum dots are employed as qubits. Excitonic states, which can be produced ultrafast with optical operation, are used as auxiliary states in the realization of quantum gates. We show how properly tailored ultrafast laser pulses and Pauli-blocking effects can be used to achieve a universal encoded quantum computing.