Quantum Dynamics Of Hybrid System For Superconducting Qubits And NV Centers

With the rapid development of information science and technology, quan-tum mechanics and information science are closely related, and thus the rise of a new cross-disciplinary-quantum information. According to the particularity of quantum theory, the emergence of Quantum Information Science in the process of information processing to speed up the computing speed, to ensure the safety of information, increase the capacity of information and improve the detection accuracy and so there is a great breakthrough. These classical limits of the break-through to complete the classic information theory in many of the past can not be achieved, making the quantum information science and to a new height. In order to better develop the information science, the quantum information science has made a great breakthrough in the practical application of life, and the realization of the quantum computer is still one of the most popular topics in the current sci-entific research. Because of the unique advantages of the superconducting qubits based on the Joseph junction superconducting circuit:Good controllability, It is easy to design such a superconducting circuit configuration, between the supercon-ducting qubits and superconducting quantum bits and other quantum system is very easy to realize strong coupling, Very good to integration. Making it one of the most outstanding elements of quantum computers. However, due to the coupling between the superconducting qubits and the environment, the system is very fast, which makes the superconducting qubits have some defects, and the coherent time is very short. Large scale quantum computation and storage of information need a long time, which requires a long time to find the quantum bit. However, the other kind of NV center, even at room temperature, can have a very long coherence time, and its robustness is very strong. Which makes it very easy to think of using their special properties, which are coupled together, combining the advantages of subsystem, at the same time broaden the shortcomings of the system to form a hybrid quantum system. At present, many domestic and foreign research teams have realized the pioneering progress in this area. On this basis, a new hybrid system is proposed to study the dynamics of hybrid systems.The structure of this thesis is arranged as follows:In the first chapter, we review the basic background and research status of quantum information, and briefly introduces some advantages of the quantum computer and some requirements for the realization of the quantum computer. This paper describes some of the seminal research results brought about by the rise of hybrid quantum systems in recent years.In the second chapter, we present some basic theoretical knowledge of quan-tum hybrid systems consisting of superconducting qubits and NV centers, and quantum information. We described the Josephson effect, followed by the intro-duction of the three kinds of superconducting quantum bit:flux qubit, charge qubit and phase qubit. And then some background and theoretical knowledge of the NV centers are introduced. Finally, we discussed the measure of the degree of quantum entanglement:quantum concurrence.In the third chapter, we investigate transfer of quantum states between two NV-center ensembles assisted by the flux qubit. We obtain the Hamiltonian of the whole hybrid system, and show that the hybrid system how to realize the trans-mission of quantum states between two NV-center ensembles by the use of the flux qubit. We discuss how to transfer an arbitrary unknown quantum state from one NV center to another under conditions of resonance and dispersion,respectively.In the fourth chapter, we studies entanglement dynamics between two NV-center ensembles and between the whole of the two NV-center ensembles and the flux qubit, respectively. It is shown thai, the dynamic evolution of quantum entan-glement is periodical, and there exists the sudden death of quantum entanglement at some specific times for two kinds of typical initial states. In particulai, we show that entangled coherent states between two NV-center ensembles can be produced by making quantum measurents upon the flux qubit.In Chapter Five, we present a summary and puts forward the prospects for future research work.