Generations, Characterizations, and Manipulation of Quantum States in Semiconductor Quantum Dots Chih-Kang (Ken) Shih Department of Physics, University of Texas at Austin Abstract: Semiconductor quantum dots (SQDs) are nanometer scale semiconductor crystals, where electrons and holes are confined in all three dimensions, leading to delta function like quantized states similar to those of atoms. For this reason, QDs are often referred to as "artificial atoms". Their atomic like optical properties together with the possibility of quantum state engineering through size, shape, and composition control, have inspired many technological applications, including the current topics of quantum computations. This talk focuses on exploration of quantum coherent phenomena in semiconductor quantum dots grown using molecular beam epitaxy (MBE). We first explore various dephasing mechanisms of excitonic states in SAQDs from which we identified an energy regime where long dephasing time exists for the excited states. We then use these long-dephasing states to demonstrate Rabi oscillations, a non-linear coherent phenomenon corresponding to a Qubit rotation. Furthermore, we explore the interplay between Rabi oscillations and quantum interferences. In this scheme, we manipulate not only the probability distribution but also the relative quantum phase between two quantum levels. Finally, we report the observation of 10 Rabi oscillations of excitonic states in QDs. The underlying physics of this successful observation and its implication for future directions are also discussed.