The Entanglement Of Two Moving Atoms Via A Three-photon Process And Distributed Quantum Computation With Superconducting Qubits

Quantum entanglement is a significant physical resources of the quantum computation and the quantum information processing, under the normal circumstances and induced by the surrounding environment, the quantum systems could be entangled, and with the environmental impact, the interaction between the environment and the quantum system, would led to de-coherence resulting the entanglement decay and death; the quantum computation and the quantum information processing also were referred to the distribution of the quantum computation, and as the mesoscopic quantum coherence has been verified experimentally, the superconducting qubits is a good candidate for the distribution of the quantum computation.In this paper, by using the quantum entanglement theory, with the interaction between the light field and the atoms, the induced entanglement and the entanglement sudden death and birth were investigated; by using the quantum computation theory, with the interaction between the dressed superconducting qubits and the LC circuits, the theoretical process and the experimental implementation of the distribution of the computation were investigated. And some significant conclusions were given below through the above studies:In chapter 1, the basic conceptions of the quantum entanglement and the quantum computation are presented. Firstly, the definition of quantum entanglement states, EPR paradox, and Bell inequality are given, the measurement of the degree of quantum entanglement are introduced; Secondly, the definition of dressed states and the fidelity, the basic quantum logic gates are given.In chapter 2, by using concurrence, the entanglement of two moving atoms induced by a single-mode field via a three-photon process is investigated. It is shown that the entanglement is dependent on the category of the field, the average photon number, the number of half-wave lengths of the field mode and the atomic initial state. Also, the sudden death and the sudden birth of the entanglement are detected in this model and the results show that the existence of the sudden death and the sudden birth depends on the parameter and the category of the mode field. In addition, the three-photon process is a higher order nonlinear process.In chapter 3, A scheme, using two superconducting qubits driven by the classical field separately interacted with two distant LC circuits connected by another LC circuit with mutual inductance, for implementing quantum gates is proposed. By using dressed states, quantum state transfer and quantum entangling gate can be implemented. With the help of the time-dependent electromagnetic field, any two dressed qubits can be selectively coupled to the data bas (the last LC circuit), then quantum state can be transferred from one dressed qubit to another and multi-mode entangled state can also be formed. As a result, the promising perspectives for quantum information processing of mesoscopic superconducting qubits are opened and the distributed and scalable quantum computation can be implemented in this scheme.In chapter 4, the conclusion and the prospect are given.