The Investigation Of Nonclassical Correlation In Superconducting Qubits Systems

Quantum information science is a new interdisciplinary subject,which involves many subjects such as quantum optics,quantum electrodynamics,informatics and mathematics.Because of its advantages over classical information in information transmission and information processing,it has attracted the attention of the scientific community and national governments,and has been developed rapidly in recent decades.Nowadays,many research achievements related to quantum communication,quantum key distribution and quantum computing have been applied to practice.For example,quantum communication based on quantum key distribution,in particular,Google recently announced that they have achieved "quantum hegemony" in some computing tasks.This paper mainly studies the contents of three parts.First,in the third chapter,we investigate the dynamics of non-classical correlations(quantum entanglement and quantum discord)of the system consisting of two non-interacting superconducting qubits coupling with a common data bus,where the system is driven by the dynamical decoupling pulses.It is found that the non-classical correlations between two superconducting qubits can be increased by applying a train of dynamical decoupling pulses.Furthermore,we also explore the influence of the dynamical decoupling pulses on the information flowing between superconducting qubits and data bus by making use of the trace distance.It is shown that the dynamical decoupling pulses can protect quantum information of two superconducting qubits and accelerate information flow back from the data bus to the superconducting qubits.Then,in the fourth chapter of the paper,taking the advantage of dynamical decoupling pulses,we investigate the non-classical correlations dynamics and quantum state transfer in atom-cavity-fiber system.It is found that the non-classical correlations and the fidelity of quantum state transfer(between the atoms)can be greatly improved by the dynamical decoupling pulses.Furthermore,it is worth noting that with decrease of the time intervals between two consecutive pulses,optimal non-classical correlations transfer and entangled state transfer can be achieved.Finally,in the fifth chapter of the paper,we study the influence of dynamical decoupling pulses on non-classical correlations(quantum entangle and quantum discord)and the quantum coherence of the cavity quantum electrodynamics system.It is found that the dynamic decoupling pulse can increase non-classical correlation and quantum coherence between two atoms in the system.Furthermore,we also study the effect of dynamic decoupling pulses on the information flow between the two atoms and the cavity in the system by trace distance.It is shown that the dynamic decoupling pulse can protect the quantum information in the two atoms and accelerate information flow back to the two atoms from the cavity.Finally,we used the fidelity of state preparation to study the three-body entanglement in the system.It is found that three-body entanglement can exist in the system and the time of three-body entanglement can be enhanced by dynamic decoupling pulse.