Non-perturbative gadget for topological quantum codes

Many-body entangled systems, in particular topologically ordered spin systems proposed as resources for quantum information processing tasks, often involve highly non-local interaction terms. While one may approximate such systems through two-body interactions perturbatively, these approaches have a number of drawbacks in practice. Here, we propose a scheme to simulate many-body spin Hamiltonians with two-body Hamiltonians non-perturbatively. Unlike previous approaches, our Hamiltonians are not only exactly solvable with exact ground state degeneracy, but also support completely localized quasi-particle excitations, which are ideal for quantum information processing tasks. Our construction is limited to simulating the toric code and quantum double models, but generalizations to other non-local spin Hamiltonians may be possible.Comment: 13 pages, 8 figures, PRL Accepte

Copying, Culture, and Control: Chinese Intellectual Property Law in Historical Context

William P. Alford, To Steal a Book is an Elegant Offense: Intellectual Property Law in Chinese Civilization. Stanford: Stanford University Press, 1995. Pp. ix, 222. $39.50. Few people are as well-suited as William Alford to provide this understanding. Now Henry L. Stimson Professor of Law and Director of East Asian Legal Studies at Harvard, Alford studied Chinese history at Yale Graduate School and law at Harvard, then practiced international law before returning to academia. Like his mentors, Jonathan Spence at Yale and Jerome Cohen at Harvard, Afford is adept at producing work that engages and stimulates both China scholars and non-specialists. The book at hand is no exception. Though relatively short in length, it is a rich, pioneering study that sets forth two distinct but closely related arguments. The first, which makes up the core of the book, explains by reference to China\u27s political culture why intellectual property law, and in particular copyright, has never taken hold in China. The second, which builds on the first and constitutes the conclusion, seeks to convince American policy makers and diplomats that without further political liberalization and a greater concomitant commitment [by the Chinese] to the institutions, personnel, interests and values needed to undergird a rights-based legality, detailed refinements in intellectual property doctrine itself will be of limited value. Thus, Alford argues, as difficult as it is for one nation to influence the enduring values and practices central to [another] nation\u27s identity, the United States ought nonetheless to attempt to nurture a new, more rights-oriented political culture in China. Afford\u27s persuasive plea for a values-driven China policy may strike some readers as ironic in light of Alford\u27s reminder at the outset of this study that, in studying legal developments in China, we should not assume that our own course of history is necessarily normal or inevitable. However, his teleological argument is devoid of the tendentiousness that might weaken its cogency. Alford\u27s work traces the story of how an enduring, paternalistic, authoritarian Chinese political culture, embodied successively by the commitments of imperial, republican, and socialist states to controlling both the flow and content of information for the purpose of sustaining state power, has impeded the development of intellectual property rights

Wetting Phase Transition at the Surface of Liquid Ga-Bi alloys: An X-ray Reflectivity Study

X-ray reflectivity measurements of the binary liquid Ga-Bi alloy reveal a dramatically different surface structure above and below the monotectic temperature $T_{mono}=222^{\circ}$ C. A Gibbs-adsorbed Bi monolayer resides at the surface at both regimes. However, a 30 {\AA} thick, Bi-rich wetting film intrudes between the Bi monolayer and the Ga-rich bulk for $T > T_{mono}$. The internal structure of the wetting film is determined with {\AA} resolution, showing a theoretically unexpected concentration gradient and a highly diffuse interface with the bulk phase.Comment: 5 RevTex pages, 3 figures, Phys. Rev. Let

Unravelling deservingness: Which criteria do people use to judge the relative deservingness of welfare target groups? A vignette-based focus group study

Previous research suggests that European citizens share consistent attitudes towards the relative deservingness of different target groups of social policy, such as perceiving elderly people as most deserving, unemployed people as less deserving and immigrants as least deserving. Yet, it is unclear which criteria people apply when making these judgements. In this article, we explore the reasoning behind deservingness judgements. We analyse how four focus groups – from the middle class, the working class, young people and elderly people – discuss and rank various vignettes representing welfare target groups. Our focus groups’ rankings mirror the well-established rank order of welfare target groups, and we also introduce further target groups: median-income families, low-income earners, and well-off earners. Our analyses of reasoning patterns show that depending on the target group specific combinations of deservingness criteria suggested in the literature (e.g. need, reciprocity, identity, control) are applied, and we suggest adding a further criterion emphasizing future returns on invested resources (‘social investment’). Furthermore, by comparing focus groups, we find that different groups back up similar rankings by differing criteria, suggesting that below the surface of a ‘common deservingness culture’ linger class and other differences in perceiving welfare deservingness.NORFACE Welfare State FuturesPeer Reviewe