The Theoretical Research Of Geometric Quantum Correlations For Cavity QED

Quantum computation and quantum information is a new interdisci-plinary subject,which carries out information tasks based on the principles of quantum mechanics.Quantum computation and quantum information has its major advantage because of the existence of the superposition principle of quantum states and quantum entanglement.How to control the quantum entanglement has become a very important research subject and a international hotspot in theory and experiment.However, quantum systems using for quantum information tasks are prone to be affected by the environment and lose entanglement,then task cannot be put into effect.Recently,a new type of quantum correlation named quantum discord is came up. It has advantages over quantum entanglement especially in the decoherence environment.In this thesis,our study is concerned with the influence brought by white-noise to geometric quantum discord between two atoms in cavity QED.For investigating the impact caused by white-noise to geometric quantum correlations,we employ two two-level atoms trapped in an optical cavity and observe the change of geometric discord correlations under the environment of white-noise. When two atoms are driven by two independent white-noise fields with the same intensity at the same time and initially in the Bell diagonal states,geometric quantum discord exhibits double changes during the time evolution. When two atoms are initially in the pure state, there are no double changes.In this situation, geometric quantum correlations are suppressed and destroyed in the end. We also research the relation between geometric quantum correlations and some parameters,such as spontaneous emission, coupling strength and so on. For further studying, if only one atom is driven by white-noise fields, geometric quantum correlations between two atoms exhibit a steady state. For weak noise intensity, geometric quantum correlations increase to a maximal value with the increase of white-noise intensity and then decrease with it. It is named stochastic-resonance-like behavior.Under the influence of spontaneous emission rate, coupling strength and Rabi frequency, geometric quantum correlations exhibit stochastic-resonance-like behavior too. So, it is possible to control the geometric quantum correlations between two atoms in the future.