Dynamics of optically driven exciton and quantum decoherence

By using the normal ordering method, we study the state evolution of an optically driven excitons in a quantum well immersed in a leaky cavity, which was introduced by Yu-xi Liu et.al. [Phys. Rev. A {\bf 63}, 033816 (2001)]. The influence of the external laser field on the quantum decoherence of a mesoscopically superposed states of the excitons is investigated. Our result shows that, thought the characteristic time of decoherence does not depend on the external field, the phase of the decoherence factor can be well controlled by adjusting the external parameters.