Superoperator Analysis of Entanglement in a Four-Qubit Cluster State

In this paper we utilize superoperator formalism to explore the entanglement evolution of four-qubit cluster states in a number of decohering environments. A four-qubit cluster state is a resource for the performance of an arbitrary single logical qubit rotation via measurement based cluster state quantum computation. We are specifically interested in the relationship between entanglement evolution and the fidelity with which the arbitrary single logical qubit rotation can be implemented in the presence of decoherence as this will have important experimental ramifications. We also note the exhibition of entanglement sudden death (ESD) and ask how severely its onset affects the utilization of the cluster state as a means of implementing an arbitrary single logical qubit rotation.Comment: 9 pages, 9 composite figures, presentation of results completely rewritte

Liberal Democracy’s Contested Development in Post-Handover Hong Kong

This thesis investigates the contested development of liberal democracy in Hong Kong since the 1997 handover of the city back to China. This is accomplished by analyzing the development of procedural democracy, press freedom, and identity in Hong Kong. These first two facets are assessed because liberal democracy entails a democratically elected government that protects liberal rights. While most rights in Hong Kong are well protected, press freedom stands out as being under threat from indirect Chinese interference. A discussion of identity then helps to predict the likely future trends for the development of liberal democracy, since the Hong Kong public is more likely to support democratization, local autonomy, and be less nationalist if it holds a stronger local Hong Kong identity than Chinese identity. Full democracy in Hong Kong has not been achieved since the major wielder of governmental power, the Chief Executive, is still not directly elected. The persistence of this democratic deficit leaves Hong Kong a ‘liberal flawed democracy,’ an international outlier among advanced economies. This has persisted due to external influence from Britain under the colonial system and then China, weaknesses in pro-democracy civil society groups and the presence of strong local pro-Beijing political organizations, and individual psychological factors. One fundamental barrier to democratization is the public’s aversion to confronting China and lack of belief in democracy as an end goal for society. Broad-based public support for democratization has therefore only arisen as a tool for preventing potential government repression. When threats of repression have subsided, mass demands for democracy have likewise diminished. Furthermore, the liberal distinction in Hong Kong’s characterization as a ‘liberal flawed democracy’ may even be under threat from Chinese influence. Since the 1990s, businessmen with economic interests in China have acquired Hong Kong media organizations and either shut them down or softened their editorial position towards China in order to win greater access to the Chinese market. Pressure has also been placed on journalists to self-censor, a growing problem in Hong Kong according to industry and public perceptions. While media censorship is limited by journalists’ strong sense of professionalism and the industry-wide Hong Kong Journalists Association’s advocacy for press freedom, the prospects for the Hong Kong media are still bleak. A weakened press unable to voice the public’s concerns also exposes other rights to interference. Tracking the development of identity in Hong Kong provides a useful gauge of how liberal democracy will progress in the future. Though a strong Hong Kong identity emerged in local popular culture in the 1970s, China placed pressure on the Hong Kong media to promote a stronger Chinese identity in the late 1980s and 1990s. Although apprehension about the handover kept Hong Kong people from immediately embracing a Chinese identity, Chinese identification did grow in the early 2000s. Since 2008, however, growing conflicts between the Hong Kong people and the Chinese government and Mainlanders has caused a strong Hong Kong identity to reemerge. This local identification seems likely to persist in the near future, encouraging the continuation of the status quo: continued public defense of liberal rights and moderate support for greater democracy. In the long term, however, China’s influence over local media and education provides it with two powerful tools for incrementally instilling greater Chinese identification. As this could expose Hong Kong’s liberal rights to interference and further stall democratic progress, these factors should be watched closely and studied further