The steady-state populalions and Ihe absorption spectrum of a V-type theree-level atom driven by a strong coherent lield lind a weak slochastic one simultaneously ale ibvestigated. The populaltion inversion in bare-sale and dressed-state bases Can happen significantly due to the effect of tile stochastic field. A relation between tile level gap of both atomic exciled slates and the Rabi frequency is found to decide in which excited state the population is lalger than in another one for the same frequency detuning δ between the coherent and the stochastic fields. The line profiles of the absorption spectrumare strognly dependent on the frquency detuing δ, Different lineshapes such as a sharp emission peak (gain). an absorption peak or a dispersion-like peak can be exhibited al the line centre for differentδ. Asymmetrical spectral features and line narrowing can be reached by adjusling δ and the Rabi frequency. Plobe gain in sidebands can occur due to the unbalanced populalion distribuitn in dressed states.

A cavity-modified master equaion is derived for a coherently driven, V-type three-level atom coupled to a single-mode cavity in the bad-cavity limit. We show that population iversionin both the bare-and dressedstate bases may be achieved, originationg form the enhancementof the acom-cavity interaction when the caivty are analyzed in terms of the cavity-modifeed transition rates.The atomic fluorescence spectrum and probe absorption spectrum are also investigated, and it is found that the spectral profiles may be controlled by adjusting the cavity frequency. Peak suppression and line narrowing occure under the appropriate conditions.

The dynamical behavior of entanglement ofr excitons in two quatum dots placed in two separately singlemode optical cavities driven by an external boradband two-mode squeezed vacuum is studied in the low exciton density regime. It is found that if the field in the two separated cavitied is initially prepared in a pure two-mode squeezed vacuum state, the excitons in the two quantum dots cna evolve into a pure entangled state only when the dissipation of the cavitied and excition modes is negligible. When the efect of the dissipation is included, the excitions will be in a two-mode Gaussian entangled mixed state whose properties are decided by the externally driven fiedld and the initial field. The dependence of the entanglement property of the excitons in the two quantum dots on the squeezing properties of the fields in the two cavities is also discussed.

The dynamical behavior of entanglement for excitonsi in two quantum dots placed in a caivty driven by a broadband squeezed vacuum is studied in the low exciton density regime. It is found that the excitions in two quantum dost can evole into a pure entangled state only when the dissipaion of the caivity and exction modes is negligible. When the injected field into the cavity is a squeezed vacuum, the exctions will be in a two-mode Gaussian entangled mixed state even in the long time limit. Analytical expressions are derived, showing the dependece of the entanglement property of the excitons in two quantum dost on the squeezing properties of th inital state prepared in the cavity and the strength of two-photon correlations of the squeezedvacuum injected into the cavity.

The time-dependent characteristic function for the vibratlonal quanta of two ions separately trapped in two caacaded optical eavities is obtained analytieally beyond the bad cavity linit, in which tfie motional mode of the ion in the first cavfiy is coupled to lhe cavity, field via an effective parametrc interacion and that of the ion in the second cavity" via a liaear-mixing interaction as proposed by Peng and Parkias Pfiys. Rev. A 65, 062323 (2002l]. It is fond, that the two ions develop in a two-mode mixed Gaussian entangle state if there exists a unidirecfional coupling from the first cavitv to the seecond one.