Theory of exciton coherence and decoherence in semiconductor quantum dots

We discuss the Rabi splitting and Rabi oscillation of excitons in semiconductor quantum dots and clarify the fundamental physics and new characteristic features. These coherent optical phenomena are not restricted to semiconductor quantum dots and the predicted features would be observed also in atoms and molecules. The universality of the phenomena ensures the possibility for application to quantum state control and quantum information processing by optical means. We discuss briefly the mechanisms of exciton dephasing in semiconductor quantum dots in conjunction with recent observations of the lifetime-limited exciton dephasing time and show that the pure dephasing rate is very small but is not vanishing even at zero Kelvin.