The Study Of Quantum Entanglement And Non-classical Effects

Quantum information science, which mainly includes quantum computer and quantum communication, has increasingly evolved as a new object. And it exhibits a number of advantages corresponding to classical counterpart. Quantum entanglement which is the basic resources of quantum information science is always researched by people.Cavity quantum electrodynamics (QED) system is overlapping research area between the atomic physics and the quantum optics. It not only can help us to understand quantum effects and reveal the interaction dynamics of atoms and optical fields, but also provide an effective tool for quantum information processing. Quantum entanglement is the phenomenon which the classical theory is unable to explain, similarly non-classical effects, which is an important content in the quantum optics. The relation between entanglement and nonclassical effects is always researched.In this thesis, we investigate entanglement dynamics in cavity quantum electrodynamics (QED) system and the relation between entanglement and the nonclassical effects. The main contents of this thesis are as follows:1. By the negativity method, we investigate the entanglement dynamics of two entangled two-level atoms that go through the high Q fields in the Fock state one by one. The results shows that the two-atom initial state and the field in the Fock state are influenced on the entanglement degree of two states and the two -atom quantum state will stay in the maximum state longer when the initial condition is proper, then make the significance comparison with the two atoms' entanglement evolutions in the condition that the two atoms are laid in QED at the same time.2. By introducing orthogonal basis, the entangled coherent states are converted to discrete ones. We calculate their entanglement by concurrence and their nonclassical effects, such as squeezing and antibunching. We find that the entanglement always follows one of squeezing and antibunching and the entanglement is increased along with the increase of one of nonclassical effects.