Coherent Manipulation Of Nanomechanical Resonators And Applications In Quantum Information

Since the appearance of quantum theory, coherent manipulation of quantum systems has become a research hotspot in physics. The development of quantum information science inspires people's research interest in coherent manipulation of quantum systems. Recently, people have been able to manipulate coherently a single quantum system due to the development of experimental conditions and techniques. Great progresses have been made in coherent manipulation of some physical systems such as cavity-QED, ion trap, and Bose-Einstein condensation. In recent years, since the derivation of solid-state quantum computation, great advances have been made in coherent manipulation of solid systems. Coherent systems such as superconducting charge qubit, double quantum dot qubits, and circuit-QED have attracted much attention. The research on coherent manipulation of quantum systems can be used to check and understand fundamental theory in quantum mechanics, as well as to dig potential applications in future technology. In this thesis, we discuss the coherent manipulation, detection of quantum properties, and possible applications in quantum information science of nanomechanical resonators. According to the properties of a given physical system, we design proper and feasible physical schemes to realize coherent manipulation and applications of nanomechanical resonators.The thesis is divided into five parts. The first part contains the second chapter where we introduce the concept, structure, and physical properties of several basic physical systems used in this thesis such as nanomechanical resonators, superconducting charge qubit, double quantum dot qubits, and circuit-QED. The second part contains both the third chapter and the fourth chapter. In this part, we show how to manipulate coherently nanomechanical resonators through controlling assistant qubits such as superconducting charge qubit and double quantum dot qubit. We propose some schemes to prepare a nanomechanical resonator into some interesting states such as squeezed vacuum state, Schrodinger cat state and entangled coherent state. The third part includes the fifth chapter. In this part, we investigate how to detect quantum nature in nanomechanical resonators. We propose a scheme to implement quantum nondemolition measurement of the number of exciton in a nanomechanical resonator. We also propose a scheme to measure the vibration nature of nanomechanical resonators: quantum or classically? The fourth part contains the sixth chapter. We discuss the applications of nanomechanical resonators in quantum information science. A nanomechanical resonator as a databus is used to couple two qubits and realize two-qubit logic gates. We also show how to implement quantum state transfer in a quantum network of nanomechanical and superconducting transmission line resonators.Chapter 7 is the fifth part. In this chapter, we conclude this thesis and give some outlook in the future.