Nature Physics January Issue

TABLE OF CONTENTS January 2012 Volume 8, Issue 1 Insight Editorial Thesis Research Highlights News and Views Commentary Reviews Progress Article Letters Articles Subscribe   Facebook   RSS   Recommend to library   Twitter   Advertisement Subscribe to Nature Physics today! For top-quality research in all areas of pure and applied physics choose Nature Physics. Subscribe online here   Insight Top Nature Physics Insight – Complexity Insight issue: January 2012 Volume 8, No1 Table of Content In many large ensembles, the property of the system as a whole cannot be understood from studying the individual entities alone — these ensembles can be made up by neurons in the brain, transport users in traffic networks or data packages in the Internet. The past decade has seen important progress in our fundamental understanding of what such seemingly disparate 'complex systems' have in common; some of these advances are surveyed here. Editorial Top Opportunities in a social world p1 doi:10.1038/nphys2204 Social networks — what are they good for? We don't know for sure, but we're keen to find out. Full Text | PDF Thesis Top It's a (stylized) fact! p3 Mark Buchanan doi:10.1038/nphys2191 Full Text | PDF Research Highlights Top Segmentation diagnosis | Guided matter | Cooling by numbers | Spot the difference | Luminous repulsion enhanced News and Views Top Quantum technology: Three-spin juggling pp5 - 6 Frank Koppens doi:10.1038/nphys2165 Manipulating the electrons trapped in quantum-dot pairs is seen as one possible route to quantum computation. This idea is now extended to three quantum dots, enabling a whole host of extended functionality. Full Text | PDF See also: Letter by Gaudreau et al. Nonlinear dynamics: We're jamming p6 Abigail Klopper doi:10.1038/nphys2193 Full Text | PDF Valley nematics: Unfinished bismuth pp7 - 8 Siddharth A. Parameswaran and Vadim Oganesyan doi:10.1038/nphys2189 Anisotropies in conductivity measurements of bismuth point to the spontaneous breaking of intrinsic degeneracies in its electronic structure — and suggest there may be still more to learn from this well-studied material. Full Text | PDF See also: Article by Zhu et al. 2D electron systems: Metals in flatland pp8 - 9 James F. Annett doi:10.1038/nphys2192 Is it possible for a metal to exist in a strictly two-dimensional system? This may seem trivial, but it is actually a longstanding problem. The electrical characteristics of an array of superconducting islands on a normal metal suggests that the answer could be 'yes'. Full Text | PDF See also: Letter by Eley et al. Topological defects: Topology in superposition pp9 - 10 K. Birgitta Whaley doi:10.1038/nphys2186 Topological defects are encountered in fields ranging from condensed-matter physics to cosmology. These broken-symmetry objects are intrinsically local, but theoretical work now suggests that non-local quantum superpositions of such local defects might arise in a quantum phase transition. Full Text | PDF See also: Letter by Dziarmaga et al. Physics JOBS of the week PhD position in experimental nuclear physics K.U.Leuven - Department of Physics and Astronomy PhD in Soft Matter Physics Wageningen UR (University & Research centre) PhD Studentships in particle physics at QMUL QMUL Software Programmer – Physics or Mathematics Paramount Recruitment Full professor, Associate Professor, Assistant Professor in Computational Physics, Surface Physics Surface Laboratory, Institute of Physics, Chinese Academy of Sciences More Science jobs from Physics EVENT Plasma Physics Group Annual Conference 2nd April - 5th April 2012 Oxford, UK More science events from Editorial Top Nature Physics Insight – Complexity Complexity p13 Andreas Trabesinger doi:10.1038/nphys2198 Full Text | PDF Commentary Top Nature Physics Insight – Complexity The network takeover pp14 - 16 Albert-László Barabási doi:10.1038/nphys2188 Reductionism, as a paradigm, is expired, and complexity, as a field, is tired. Data-based mathematical models of complex systems are offering a fresh perspective, rapidly developing into a new discipline: network science. Full Text | PDF Reviews Top Nature Physics Insight – Complexity Between order and chaos pp17 - 24 James P. Crutchfield doi:10.1038/nphys2190 A completely ordered universe is as unexciting as an entirely disordered one. Interesting 'complex' phenomena arise in a middle ground. This article reviews the tools that have been developed to quantify structural complexity and to automatically discover patterns hidden between order and chaos. Abstract | Full Text | PDF Nature Physics Insight – Complexity Communities, modules and large-scale structure in networks pp25 - 31 M. E. J. Newman doi:10.1038/nphys2162 Networks have proved to be useful representations of complex systems. Within these networks, there are typically a number of subsystems defined by only a subset of nodes and edges. Detecting these structures often provides important information about the organization and functioning of the overall network. Here, progress towards quantifying medium- and large-scale structures within complex networks is reviewed. Abstract | Full Text | PDF Nature Physics Insight – Complexity Modelling dynamical processes in complex socio-technical systems pp32 - 39 Alessandro Vespignani doi:10.1038/nphys2160 Vast amounts of data are available about complex technological systems and how we use them. These data provide the basis not only for mapping out connectivity patterns, but also for the study of dynamical phenomena, including epidemic outbreaks and routing of information through computer networks. This article reviews the fundamental tools for modelling such dynamical processes and discusses a number of applications. Abstract | Full Text | PDF Progress Article Top Nature Physics Insight – Complexity Networks formed from interdependent networks pp40 - 48 Jianxi Gao, Sergey V. Buldyrev, H. Eugene Stanley and Shlomo Havlin doi:10.1038/nphys2180 Aspects concerning the structure and behaviours of individual networks have been studied intensely in the past decade, but the exploration of interdependent systems in the context of complex networks has started only recently. This article reviews a general framework for modelling the percolation properties of interacting networks and the first results drawn from its study. Abstract | Full Text | PDF See also: Article by Zhu et al. Letters Top Non-local quantum superpositions of topological defects pp49 - 53 Jacek Dziarmaga, Wojciech H. Zurek and Michael Zwolak doi:10.1038/nphys2156 So-called topological defects appear in various forms, be it as monopoles, cosmic strings, vortex lines or domain walls. This work suggests that such localized entities can be put in non-local superpositions, and describes the decoherence behaviour of such quantum states. First paragraph | Full Text | PDF See also: News and Views by Whaley Coherent control of three-spin states in a triple quantum dot pp54 - 58 L. Gaudreau, G. Granger, A. Kam, G. C. Aers, S. A. Studenikin, P. Zawadzki, M. Pioro-Ladrière, Z. R. Wasilewski and A. S. Sachrajda doi:10.1038/nphys2149 Manipulating the electrons trapped in quantum-dot pairs is one possible route to quantum computation. Translating this idea to three quantum dots would enable a whole host of extended functionality. Researchers now generate and manipulate coherent superpositions of quantum states using the spins across three electrical-gate-defined dots. First paragraph | Full Text | PDF See also: News and Views by Koppens Approaching zero-temperature metallic states in mesoscopic superconductor-normal-superconductor arrays pp59 - 62 Serena Eley, Sarang Gopalakrishnan, Paul M. Goldbart and Nadya Mason doi:10.1038/nphys2154 It has long been debated whether it is possible to approach a zero-temperature metallic state in a two-dimensional system. A study of the electrical characteristics of arrays of superconducting islands of varying thickness and spacing on a normal metal film suggests it is. First paragraph | Full Text | PDF See also: News and Views by Annett Two-stage orbital order and dynamical spin frustration in KCuF3  pp63 - 66 James C. T. Lee, Shi Yuan, Siddhartha Lal, Young Il Joe, Yu Gan, Serban Smadici, Ken Finkelstein, Yejun Feng, Andrivo Rusydi, Paul M. Goldbart, S. Lance Cooper and Peter Abbamonte doi:10.1038/nphys2117 Orbital order is important to many correlated electron phenomena, including colossal magnetoresistance and high-temperature superconductivity. A study of a previously unreported structure transition in KCuF3 suggests that direct interorbital exchange is important to understanding such order. First paragraph | Full Text | PDF Topological semimetal in a fermionic optical lattice pp67 - 70 Kai Sun, W. Vincent Liu, Andreas Hemmerich and S. Das Sarma doi:10.1038/nphys2134 Experimental progress has made it possible to load fermionic atoms into higher orbital bands. Such systems provide a platform for studying quantum states of matter that have no prior analogues in solid-state materials. This theoretical study predicts a semimetallic topological state in these systems, which can be turned into a topological insulating phase. First paragraph | Full Text | PDF Quantum phase transition to unconventional multi-orbital superfluidity in optical lattices pp71 - 75 Parvis Soltan-Panahi, Dirk-Sören Lühmann, Julian Struck, Patrick Windpassinger and Klaus Sengstock doi:10.1038/nphys2128 The behaviour of molecules and solids is governed by the interplay of electronic orbitals. Superfluidity, in contrast, is typically considered a single-orbital effect. Now, a combined experimental and theoretical study provides evidence for a multi-orbital superfluid, with a complex order parameter, occurring in a binary spin mixture of atoms trapped in an hexagonal optical lattice. First paragraph | Full Text | PDF Attoclock reveals natural coordinates of the laser-induced tunnelling current flow in atoms pp76 - 80 Adrian N. Pfeiffer, Claudio Cirelli, Mathias Smolarski, Darko Dimitrovski, Mahmoud Abu-samha, Lars Bojer Madsen and Ursula Keller doi:10.1038/nphys2125 A quantum particle can tunnel through an energy barrier that it would otherwise be unable to surmount. This phenomenon has an important role in atomic processes such as ionization. Researchers now use an attosecond 'clock' to take a precise look at the dynamics of this process and identify the trajectory taken by the escaping electron. First paragraph | Full Text | PDF Articles Top Enhanced electric conductivity at ferroelectric vortex cores in BiFeO3  pp81 - 88 Nina Balke, Benjamin Winchester, Wei Ren, Ying Hao Chu, Anna N. Morozovska, Eugene A. Eliseev, Mark Huijben, Rama K. Vasudevan, Petro Maksymovych, Jason Britson, Stephen Jesse, Igor Kornev, Ramamoorthy Ramesh, Laurent Bellaiche, Long Qing Chen and Sergei V. Kalinin doi:10.1038/nphys2132 The controlled creation of one-dimensional conductive channels at the cores of topological defects in the multiferroic material BiFeO3 demonstrates that such defects can drive metal-insulator phase transitions, and might provide a route towards high-density information storage. Abstract | Full Text | PDF Field-induced polarization of Dirac valleys in bismuth pp89 - 94 Zengwei Zhu, Aurélie Collaudin, Benoît Fauqué, Woun Kang and Kamran Behnia doi:10.1038/nphys2111 Multiple valleys in the electronic structure of certain crystal lattices could enable the development of so-called valleytronic devices. But to do so, the degeneracy of these valleys must be lifted. Measurements of the anisotropic magnetoelectric response of bismuth suggest that its three-fold valley degeneracy breaks spontaneously at low temperatures and high fields. Abstract | Full Text | PDF See also: News and Views by Parameswaran & Oganesyan Collisionless shocks in laser-produced plasma generate monoenergetic high-energy proton beams pp95 - 99 Dan Haberberger, Sergei Tochitsky, Frederico Fiuza, Chao Gong, Ricardo A. Fonseca, Luis O. Silva, Warren B. Mori and Chan Joshi doi:10.1038/nphys2130 Laser-driven proton accelerators could enable more effective cancer treatment, but to fulfil this function proton beams with a higher energy and narrower energy spread will need to be produced. Discovery of a laser-plasma acceleration mechanism that generates 20 MeV proton beams with a 1% spread is a promising step. Abstract | Full Text | PDF Top Advertisement NCI Physical Sciences in Oncology Reprint Collection This reprint collection brings together a selection of articles funded by the Physical Sciences–Oncology Centers programme, a network of research centres launched by the National Cancer Institute to explore ways in which physical sciences perspectives could be applied to the study of cancer. Access the collection free online for 6 months Produced with support from Office of Physical Sciences-Oncology/Center for Strategic Scientific Initiatives/Office of the Director/ National Cancer Institute   Natureevents is a fully searchable, multi-disciplinary database designed to maximise exposure for events organisers. The contents of the Natureevents Directory are now live. The digital version is available here. Find the latest scientific conferences, courses, meetings and symposia on natureevents.com. 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