Light And Some Of The Problems Of The Atomic Interactions

Quantum entanglement is one of the most remarkable characters of quantum mechanics, is also a very important resource in quantum communication. It has important applications in quantum teleportation quantum dense coding quantum error-correcting quantum secret sharing and quantum computation, which belong to the disposal of quantum communication. The measurement of quantum entanglement is also one of the subjects that people are studying, now. People have put forward several generation schemes of two-particle or several-particle entanglement using quantum electrodynamics method in recent years. Many people have studied the characters of atom entanglements in several models. Photon antibunching effect is a typical non-classical character of photon field, is also one of the most noticeable new phenomenon in photon number statistics. This quantum effect has important applications not only in opening out the quantum essence of light, but also has potential application foreground in light communication the detection of tiny signals the study in the field of people seeing system, and so on. So the theoretical study of photon antibunching effect is at all times a very popular subject in the field of quantum optics. In recent years, the photon antibunching effect in many theoretical models has been discussed hotly.For J-C and T-C model, there were already many people have studied their qualities of entanglement and non-classical characters. We have designed a new kind of model in this paper: Atoms 1 and 2 was entangled initial and were independent with atom 3. The single-mode field was in fock state. For this system, we mainly investigated the evolution of the atom entanglement and the questions of photon antibanching effect. The main contents of this thesis are as fellow:1. First, we introduced two typical models about the interaction of optical field and atoms: J-C model and T-C model. Then, we introduced some knowledge of nonclassical field and quantum entanglement. We also explained the way of measuring quantum entanglement in partialtransposition negative eigenvalue method.2. Atoms 1 and 2 was entangled initial and were independent with atom 3. The single-mode field was in fock state. For this system, we studied the time evolution of atoms entanglement when atoms 2 and 3 were in the field. Using partial transposition negative eigenvalue method, we obtained that the entanglement was related strongly with the initial states of the three atoms the photon numbers of the field and the coupling constants between atoms and cavity.3. We studied the antibunching effects of the field, which we have mentioned in the above. We gave out the pictures of time evolution for second-order correlation function with different photon numbers, initial entanglements of atoms 1 and 2 initial states of atom 3. From the analysis of the picture, we got the result: non-classical characters of the field got obvious stronger with the increase of photon numbers;when the photon number was zero, the non-classical characters of the field got weaken with the increase of initial entanglements of atoms 1 and 2 the initial coefficients of excited state in atom 3, get stronger with the increase of the ratio between coupling constants g among atoms and cavity and interactional intensity Ω between atom and atom.