Theory of coherent optical control of exciton spin dynamics in a semiconductor dot

We use the spin-polarized excitons in a single quantum dot to design optical controls for basic operations in quantum computing. We examine the ultrafast nonlinear optical processes required and use the coherent nonlinear optical responses to deduce if such processes are physically reasonable. The importance and construction of an entangled state of polarized exciton states in a single quantum dot is explained. We put our proposal in perspective with respect to a number of theoretical suggestions of utilizing the semiconductor quantum dots.