| Tavis-Cummings model, which is based on Jaynes-Cummings model (a model for one identical two-level atom interacting with single field) deals with the interaction between two identical two-level atoms and single mode field. It can not only solve more complicated and realistic problems but also exists some precise results. It has both theoretical and experimental significance, so more attentions have been paid to it.Since 1990s, Quantum information science, which mainly includes quantum computer and quantum communication, has evolved as a new research field. Because the carrier of information in this subject is quantum state, all the problems related to information should be resolved by means of quantum theory. Therefore, quantum information science exhibits a number of advantages corresponding to its classical counterpart. For example, because of the feature of quantum superposition, scientists have developed some skillful parallelism arithmetic, which can be used to resolve efficiently some hard problems for classical computers, such as factorization of large numbers and the simulation of a complicated quantum system. In addition, the existence of quantum non-cloning theorem leads to the birth of quantum cryptograph. In principal, quantum cryptograph can provide perfect secure and unassailable secret communication system, which is guaranteed by the law of quantum mechanics. Furthermore, quantum communication is a very important branch of quantum information. At present, it mainly contains quantum teleportation, quantum dense coding, quantum secret sharing, quantum key distribution, and so on. In the past few years, a surprise progress was made both in theoretical and experimental fields, which has attracted much attention of academe, information industry, and the government ofmany countries.The content of this paper is a combination of T-C model and quantum information. We study some quantum optical and quantum informational problems in T-C model. The main results of this thesis are as follows:1. We study the spontaneous emission and quantum entangled state of the system in which a two-level atom interacts with electromagnetic field. The expectation value of atom dipole moment is always zero, but the fluctuation of dipole moment is a constant and not zero during the atomic spontaneous emission. Therefore the spontaneous emission of atoms is caused by the fluctuation of dipole moment that arises from vacuum fluctuation. Jaynes-Cummings Model is an important system to produce quantum-entangled state. We find that information entropy and the amount of entanglement oscillate with time-evolution periodically. The quantum state changes between disentangled state and entangled state. The quantum state will stay in the most entangled state for a long time when the detuning is proper.2. We study the evolution property of the field entropy and the atomic in formation entropy squeezing in the T-C model. When the field stays in coherent light field and two atoms stay in coherent superposition state initially we solve the field entropy and the components of atomic information entropy precisely and calculate entropy squeezing numerically. We obtain that the field entropy and the atomic information entropy squeezing will change with the variation of systemic initial state, intensity of the light field and coupling coefficients.3. We get three-qubit entangled state in T-C model for two identically steady two-level atoms interacting with single mode field when the initial state is special. By analyzing 3-tangle of the system we obtain that the 3-tangle of the system will change with the variation of system initial stale, coupling coefficients between atom and field or atoms.Especially, when the initial state is special the system will stay in W-entangied state. We get the necessary condition for W-state.4. We study the quantum entanglement of the T-C model for two steady identical two-level atoms interacting with single mode field. When the field is vacuum and two atoms stay in EPR entangled... |
PDF Full Text Request