Quantum Information Processing Based On Quantum Non-demolition Measurement Of Superconducting Circuit

Quantum information theory has developed rapidly since the 1980s,and gradually formed a complete theoretical system in the 1990s.This emerging discipline based on quantum mechanics,challenges the classical theory with the unlimited prospects at the same time.People gradually found some unique physical propertiesin the quantum scale,such as quantum entanglement,No-cloning Theorem,superposition and coherence of quantum states,which can be applied in the field of information,in such aspects as information computation,storage and reading are much better than the classical method.For example,the use of quantum state superposition of parallel algorithm can improve computing speed index,and the use of No-cloning Theorem can complete absolute encrypted transmission of information,and the use of the quantum measurement can greatly improve the accuracy of measurement,and break through the standard quantum limitsand so on.There are many difficulties in the field of quantum information,such as the integration and expansion of the quantum bit,the reading efficiency of information storage,the decoherence cased by the interaction of qubits with the external environment and so on.Superconducting circuit system is a hot field in the field of quantum information research because of its superior performance,and the core of superconducting circuit system is the application of superconducting Josephson junction.This paper discussed he quantum information processing of the superconducting circuit system,the properties of Josephson junction and the quantum non-demolition measurement,as well as its application prospects.The main work involves the following aspects:1.The time of the superconducting quantum bit decoding is relatively short,and the quantum bit information can be written into a cavity with long decoherence,which can improve the efficiency of quantum computation.For the cavity QED system,which is composed of the superconducting charge qubits and the superconducting transmission line cavity,the condition of the quantum nondestructive measurement is analyzed by using the circuit quantum electrodynamics principle,and the preparation of the Fock state and its arbitrary superposition state is completed by the quantum non-demolition measurement.2.During the fabrication process,the coupling coefficient of superconducting qubit and waveguide,detuning and other parameters will affect the state of photons in the waveguide,and have a certain effect on the preparation of the states.In this paper,we further discuss the influence of system parameters,such as the intensity of interaction and detuning,on the preparation of Fock states.3.The preparation process needs controllable initial state,and the cavity relaxation to ground state is required after each preparation,which greatly affects the preparation efficiency.In this paper,a method of rapid preparation of Fock state by feedback response mechanism is proposed.The success rate of preparation is increased and the preparation time is shortened.