Browsing by Author "Wang, Qian"
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Item Quantum tunneling, quantum computing, and high temperature superconductivity(Texas A&M University, 2005-02-17) Wang, QianIn this dissertation, I have studied four theoretical problems in quantum tunneling, quantum computing, and high-temperature superconductivity. I have developed a generally-useful numerical tool for analyzing impurity-induced resonant-state images observed with scanning tunneling microscope (STM) in high temperature superconductors. The integrated tunneling intensities on all predominant sites have been estimated. The results can be used to test the predictions of any tight-binding model calculation. I have numerically simulated two-dimensional time-dependent tunneling of a Gaussian wave packet through a barrier, which contains charged ions. We have found that a negative ion in the barrier directly below the tunneling tip can deflect the tunneling electrons and drastically reduce the probability for them to reach the point in the target plane directly below the tunneling tip. I have studied an infinite family of sure-success quantum algorithms, which are introduced by C.-R. Hu [Phys. Rev. A {\bf 66}, 042301 (2002)], for solving a generalized Grover search problem. Rigorous proofs are found for several conjectures made by Hu and explicit equations are obtained for finding the values of two phase parameters which make the algorithms sure success. Using self-consistent Hartree-Fock theory, I have studied an extended Hubbard model which includes quasi-long-range Coulomb interaction between the holes (characterized by parameter V). I have found that for sufficiently large V/t, doubly-charged-antiphase-island do become energetically favored localized objects in this system for moderate values of U/t, thus supporting a recent conjecture by C.-R. Hu [Int. J. Mod. Phys. B {\bf 17}, 3284 (2003)].Item Who sets the news agenda on “Chinese Twitter”? The relationships between the media and opinion leaders on Weibo(2016-05) Wang, Qian; Coleman, Renita; Sylvie, George; Bock, Mary; Chen, Gina; Jang, YuriWithin the theoretical framework of agenda setting, this dissertation used granger causality analysis to examine the relationships between news agendas of the media outlets and opinion leaders on one Chinese social network platform—Weibo. It also utilized network analysis to compare agenda-setting effects between the media outlets and opinion leaders in crisis and non-crisis news. The study not only applied agenda setting to Chinese social media, but it also approached the agenda-setting effects of social media from a completely different perspective, recognizing and differentiating the segmented agendas on social media platforms. It examined more nuanced agenda-setting effects among the most influential groups on social media platforms, determining and comparing the news agendas of these groups. The results showed agenda-setting effects exist only between the opinion leaders and commercial media outlets rather than the official media in China. Although journalists and celebrities tended to be the most influential ones on Twitter, business elites were the most influential opinion leader on Weibo. Furthermore, the agenda-setting process among these opinion leaders changed in crisis and non-crisis news.