Quantum Correlation And Information Transport In Spin Boson Systems

In this thesis, the quantum correlations and the quantum information trans-port far from equilibrium are investigated in several important kinds of spin-boson systems. We know that matter-wave interaction attracted persistent attention in quantum physics. With the tremendous emergence of the quantum informa-tion area, interaction between light (mechanical wave) and matter is extensively studied ranging from condensed matter phys, quantum optics to quantum de-coherence in complex systems. Starting from the perspective of the quantum information, we mainly discuss novel features of typical systems, including the connection between the quantum correlation with the quantum phase transition in collective spin systems, dynamical characters of the quantum correlation in spin-boson models, and quantum information transport control in double quan-tum dot-mechanical oscillator coupling system far from equilibrium. In the first chapter, we briefly introduce spin-boson model, basic concepts of the quantum correlation, and descriptions of dynamical methods for open quantum systems. The main contents of this thesis are involved in the following three aspects:●In chapter two, based on successful applications of the quantum discord on the quantum phase transition, we mainly study the novel features of the discord on different phases in collective spin systems. The finite size scaling features of the discord near the critical point are analyzed in detail, and the comparisons with the quantum entanglement are carefully made. The results at first illustrate that the discord itself is able to exhibit universal scaling characters, and the corresponding first order derivative shows loga-rithmic divergence, which is quite similar with other low dimensional critical systems. Furthermore, the discord is more robust than the entanglement in the deep coherent-excitation regime.●In chapter three, we exactly analyze the dynamical features of the quantum correlations in the single mode limit Jaynes-Cummings model and spin-boon model in various environments by using both analytical and numerical ap-proaches. For the single mode case, we find the quantum correlation shows different behaviors by comparing the common bath with the independent baths, and non-resonance plays the important role on the stabilization of the discord. For the continuous modes, we investigate the quantum cor-relation particularly in the strong system-bath interaction with hierarchy equation base on the well-known Feynman-Vernon influence functional, and the Markov and non-Markov effects are considered on the changes of dy-namical behaviors.●In chapter four, combining the extended coherent bosonic state and the counting auxiliary field, we study the current fluctuations of the double quantum dot-mechanical oscillator coupling system far from equilibrium. By apply the fluctuations we try to reveal the efficiency of the quantum in-formation transport. Besides, we exploit new method about how to operate the embedded qubit in the quantum dot,to better control this information motion.●In chapter five, we give a concise summary and prospect for the thesis.