Preparation Of Entangled States Via Quantum Zeno Dynamics In Cavity QED System

Quantum information science is a extremely active science in a field of research called quantum physics,which combines quantum mechanics and classical informatics.In recent years,the emerging discipline broke out enormous research potential,it has achieved great development and breakthroughs in its various research,such as quantum computing,quantum communication,and so on.Preparation of quantum entanglement is an indispensable part of quantum information processing.The cavity quantum electrodynamics(QED)system is an ideal physical system for entangled states preparation and quantum logic gate.The system has a great developed and breakthroughs either in theory or experiment,which can be strong support for the development of quantum information science.Quantum Zeno dynamics can effectively suppress decoherence in the process of achieving a quantum operation.Cavity QED systems and quantum Zeno dynamics can be effectively combined to study quantum information processing,such as entangled states preparation and quantum logic gate.Consequently,in this thesis,we focus on how to apply quantum Zeno dynamics into cavity QED system to achieve generation of quantum entangled states.The main content of this thesis is organized as follows:In Chapter 1,we introduce the elementary concepts of quantum entanglement and the common forms of quantum entangled states,and emphatically introduce high-dimensional entangled states and atomic ensemble to highlight their advantages.And we simply introduce the concepts of picture and fidelity in this paper involved.The major research subjects and the organization of the dissertation are given at the end of this chapter.In Chapter 2,we introduce the basic knowledge of cavity QED systems and quantum Zeno dynamics.In the first section of Chapter 2,we introduce the development of cavity QED system,and emphatically introduce the cavity-fiber coupled systems,the development and the advantages of the systems.Besides,we make a brief introduction of Jaynes-Cummings(J-C)model in cavity QED systems.In the second section of Chapter 2,we firstly make a brief introduction about the history of quantum Zeno dynamics.Moreover,we verify the quantum Zeno effect from the one-dimensional projection and finite-dimensional projection,and explains how to get the quantum Zeno dynamics,focuses on the continuous coupling cases of quantum Zeno dynamics.In Chapter 3,we propose a scheme to generate Greenberger-Horn-Zeilinger(GHZ)state for four atoms trapped in a bimodal cavity.The quantum qubits are encoded in the low states,to reduce the influences of atomic spontaneous emission during the process.Numerical simulation demonstrates that our scheme is robust against the fluctuations of some parameters in a real experiment.It also shows that our scheme is insensitive to the cavity decay.In Chapter 4,we put forward a scheme for generating a three-dimensional entanglement between a single atom and an atomic ensemble via quantum Zeno dynamics in the cavity-fiber-cavity system.In this chapter,we use an atomic ensemble with a large amount of identical atoms as the basic system.The numerical simulations clearly testify that the presented scheme is robust against changes of the experimental parameters.Meanwhile,it also shows that our scheme is not sensitive to the cavity decay and the fiber loss.