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Showing papers in "Contemporary Physics in 2011"


Journal ArticleDOI
TL;DR: In this paper, the authors review the most important WISPs, the present and future experiments, the indirect hints from astrophysics and cosmology pointing to the existence of WISP, and finally outlining the consequences that the discovery of WisPs would have.
Abstract: Shining light through walls? At first glance this sounds crazy. However, very feeble gravitational and electroweak effects allow for this exotic possibility. Unfortunately, with present and near future technologies the opportunity to observe light shining through walls via these effects is completely out of question. Nevertheless there are quite a number of experimental collaborations around the globe involved in this quest. Why are they doing it? Are there additional ways of sending photons through opaque matter? Indeed, various extensions of the standard model of particle physics predict the existence of new particles called WISPs - extremely weakly interacting slim particles. Photons can convert into these hypothetical particles, which have no problems to penetrate very dense materials, and these can reconvert into photons after their passage - as if light was effectively traversing walls. We review this exciting field of research, describing the most important WISPs, the present and future experiments, the indirect hints from astrophysics and cosmology pointing to the existence of WISPs, and finally outlining the consequences that the discovery of WISPs would have.

189 citations


Journal ArticleDOI
TL;DR: X-ray microscopes can provide elemental maps and/or chemical sensitivity in samples that are too thick for electron microscopy as discussed by the authors, however, in high resolution imaging of radiation-sensitive material the effects of radiation damage needs to be carefully considered.
Abstract: The development of high brightness X-ray sources and high resolution X-ray optics has led to rapid advances in X-ray microscopy. Scanning microscopes and full-field instruments are in operation at synchrotron light sources worldwide, and provide spatial resolution routinely in the 25–50 nm range using zone plate focusing elements. X-ray microscopes can provide elemental maps and/or chemical sensitivity in samples that are too thick for electron microscopy. Lensless techniques, such as diffraction microscopy, holography and ptychography are also being developed. In high resolution imaging of radiation-sensitive material the effects of radiation damage needs to be carefully considered. This article is designed to provide an introduction to the current state and future prospects of X-ray microscopy for the non-expert.

122 citations


Journal ArticleDOI
TL;DR: In this paper, the authors provide an overview of material and electrical considerations for the design of micro-fabricated ion trap structures, and provide guidance in how to choose the appropriate fabrication design, consider dierent methods for the fabrication of micro fabricated ion traps and discuss previously realized structures.
Abstract: Ion traps offer the opportunity to study fundamental quantum systems with high level of accuracy highly decoupled from the environment. Individual atomic ions can be controlled and manipulated with electric elds, cooled to the ground state of motion with laser cooling and coherently manipulated using optical and microwave radiation. Microfabricated ion traps hold the advantage of allowing for smaller trap dimensions and better scalability towards large ion trap arrays also making them a vital ingredient for next generation quantum technologies. Here we provide an introduction into the principles and operation of microfabricated ion traps. We show an overview of material and electrical considerations which are vital for the design of such trap structures. We provide guidance in how to choose the appropriate fabrication design, consider dierent methods for the fabrication of microfabricated ion traps and discuss previously realized structures. We also discuss the phenomenon of anomalous heating of ions within ion traps, which becomes an important factor in the miniaturization of ion traps.

92 citations


Journal ArticleDOI
TL;DR: In this article, the authors review the properties of microcavity exciton-polariton condensates and discuss the question of superfluidity in a non-equilibrium system, reviewing both the experimental attempts to investigate superfluidity to date, and the theoretical conjectures.
Abstract: We review, aiming at an audience of final year undergraduates, the phenomena observed in, and properties of, microcavity exciton–polariton condensates. These are condensates of mixed light and matter, consisting of superpositions of photons in semiconductor microcavities and excitons in quantum wells. Because of the imperfect confinement of the photon component, exciton–polaritons have a finite lifetime, and have to be continuously re-populated. Therefore, exciton–polariton condensates lie somewhere between equilibrium Bose–Einstein condensates and lasers. We review in particular the evidence for condensation, the coherence properties studied experimentally, and the wide variety of spatial structures either observed or predicted to exist in exciton–polariton condensates, including quantised vortices and other coherent structures. We also discuss the question of superfluidity in a non-equilibrium system, reviewing both the experimental attempts to investigate superfluidity to date, and the theoretical sugg...

78 citations


Journal ArticleDOI
TL;DR: The first hard X-ray free electron laser (LCLS) facility at the Stanford Linear Accelerator Centre (SLAC) as discussed by the authors has been used to perform structural dynamics and nanoscale imaging.
Abstract: The arrival of the first hard X-ray free electron laser facilities promises new advances in structural dynamics and nanoscale imaging that will have impact across the sciences. This introductory review is intended to cover the basic physics behind this potential and illustrate the current state-of-the-art by discussing a number of recent findings from the LCLS facility at the Stanford Linear Accelerator Centre (SLAC). We concentrate on the new science using these light sources rather than the new light source technology itself, although a brief introduction to the operation of LCLS is given. Emphasis is placed upon the new regime of high intensity X-ray matter interaction physics with ultrashort X-ray pulses. We discuss how the unique combination of X-ray parameters will open new opportunities for time resolved structural studies and how the high brightness enables a new class of coherent diffraction X-ray imaging. The potential importance of this new imaging method in the study of nanostructures and biol...

54 citations


Journal ArticleDOI
TL;DR: In this paper, the basic building blocks of quantum information processing with cold trapped atomic ions are reviewed and methods to implement single qubit rotations and two-qubit entangling gates, which form a universal set of quantum gates.
Abstract: In this tutorial we review the basic building blocks of Quantum Information Processing with cold trapped atomic ions. We mainly focus on methods to implement single-qubit rotations and two-qubit entangling gates, which form a universal set of quantum gates. Different ion qubit choices and their respective gate implementations are described.

52 citations


Journal ArticleDOI
Bill Barnes1
TL;DR: Optical Properties of Solids, 2nd edn., by Mark Fox, Oxford, Oxford University Press, 2010, 412 pp., £55.00 (hardback), ISBN 978-0-199-57336-3 as discussed by the authors.
Abstract: Optical Properties of Solids, 2nd edn., by Mark Fox, Oxford, Oxford University Press, 2010, 412 pp., £55.00 (hardback), ISBN 978-0-199-57336-3. Scope: monograph. Level: undergraduate, postgraduate,...

47 citations


Journal ArticleDOI
TL;DR: A review of the Revolutions that made the Earth can be found in this article, where Lenton and Watson present a monograph on the history of the world's first revolution.
Abstract: A review of Revolutions That Made the Earth, by T. Lenton and A. Watson, Oxford, Oxford University Press, 2011, xii + 423 pp., £29.95 (hardback), ISBN 978 0 19 958704 9. Scope: monograph. Level: ge...

47 citations


Journal ArticleDOI
TL;DR: The local equilibrium hypothesis is a very successful basis for non-equilibrium thermodynamics over a wide range of phenomena and physical situations as mentioned in this paper, however, the increasing interest in small systems in nanotechnology, in rarefied gases in high-altitude aeronautics, or the search for new materials with sophisticated internal microstructures and tailored thermal properties have led one to ask about the limits of validity of this hypothesis, and to go beyond it.
Abstract: The local equilibrium hypothesis is a very successful basis for non-equilibrium thermodynamics over a wide range of phenomena and physical situations. However, the increasing interest in small systems in nanotechnology, in rarefied gases in high-altitude aeronautics, in high-frequency behaviour in information processing, or the search for new materials with sophisticated internal microstructures and tailored thermal properties have led one to ask about the limits of validity of this hypothesis, and to go beyond it. Here we do so in a constructive way, i.e. not only pointing out at these limits, but also embedding the local-equilibrium theory in a more general framework which explicitly exhibits these limits and suggests how to go beyond them, in search for a wider range of applications and a deeper understanding of the foundations.

40 citations


Journal ArticleDOI
TL;DR: The NIST Handbook of Mathematical Functions as discussed by the authors is the most widely used reference work for mathematical functions, with a focus on the problem of mathematical functions and its application in computer science.
Abstract: NIST Handbook of Mathematical Functions, edited by Frank W.J. Olver, Daniel W. Lozier, Ronald F. Boisvert, Charles W. Clark, Cambridge, Cambridge University Press, 2010, 968 pp., £35.00 (paperback)...

38 citations


Book ChapterDOI
TL;DR: This chapter starts with explaining the contribution of dispersion forces to the total van der Waals force between atoms and molecules, and discusses the origin of the van Der Waals-dispersion force between the neutral molecules.
Abstract: This chapter presents an overview of van der Waals forces and their role in various molecular phenomena. There are three distinct types of forces that contribute to the total long-range interaction between polar molecules, which are collectively known as the van der Waals force. These three forces include the induction force, the orientation force, and the dispersion force. Each force has an interaction free energy that varies with the inverse sixth power of the distance. Unlike gravitational and Coulomb forces, van der Waals forces are not generally pairwise additive. The force between any two molecules is affected by the presence of other molecules nearby, so simple addition of all the pair potentials of a molecule does not give net interaction energy with all the other molecules. This chapter starts with explaining the contribution of dispersion forces to the total van der Waals force between atoms and molecules. The chapter explores important features of van der Waals forces and discusses the origin of the van der Waals-dispersion force between the neutral molecules. The van der Waals equation of states was also explained.

Journal ArticleDOI
TL;DR: A review of Quantum Aspects of Life, edited by D. Abbott, P.C. Davies and A.K. Pati, London, Imperial College Press, 2008, xxvi + 442 pp., £35.00 (paperback), ISBN 978 1 84816 267 9.
Abstract: A review of Quantum Aspects of Life, edited by D. Abbott, P.C.W. Davies and A.K. Pati, London, Imperial College Press, 2008, xxvi + 442 pp., £35.00 (paperback), ISBN 978 1 84816 267 9. Scope: edite...

Journal ArticleDOI
TL;DR: In this paper, the authors survey the relationship between sound and light rays and geometry and show how sound rays in a stratified atmosphere with a wind can be mapped to a problem of circles and straight lines.
Abstract: We survey the close relationship between sound and light rays and geometry. In the case where the medium is at rest, the geometry is the classical geometry of Riemann. In the case where the medium is moving, the more general geometry known as Finsler geometry is needed. We develop these geometries ab initio, with examples, and in particular show how sound rays in a stratified atmosphere with a wind can be mapped to a problem of circles and straight lines.

Journal ArticleDOI
TL;DR: The concept of phase is deeply instilled in the mind of every physics student from a very early age and its measurement seems inevitably intertwined with the need to perform interferometry as discussed by the authors.
Abstract: The concept of phase is deeply instilled in the mind of every physics student from a very early age and its measurement seems inevitably intertwined with the need to perform interferometry. More recently, a number of important phase visualisation and measurement techniques have emerged that do not require interference. This paper introduces the concept of phase by treating it as a potential that determines the flow of energy, which leads to the idea that phase can be measured by observing the evolution of the intensity of the light on propagation. The ideas have found application in a number of areas, including optical, X-ray, neutron and electron imaging physics and these are explained.

Journal ArticleDOI
TL;DR: In this paper, the holographic approach was used to construct isolated optical vortex knots, which can be linked or knotted, and the presence of such a knot has implications for the topology of the whole field.
Abstract: When multiple light beams overlap in three-dimensional space, their interference produces tangled lines of complete darkness. These lines are called optical vortices and may be infinitely long, or form closed loops which can be linked or knotted. The vortex lines can be obtained from combining random waves (such as optical speckle). Alternatively, specific configurations of looped, linked or knotted vortex lines may be produced using holographic techniques to implement mathematically derived constructions. In the random superpositions, numerical experiments indicate that the tangle of vortex lines has a fractal nature, whereas the holographic approach allows the construction of isolated optical vortex knots. The presence of such a knot has implications for the topology of the whole field. Whether such topological features produced by interfering waves are merely curiosities or correspond to subtle physical phenomena remains an open question.

Journal ArticleDOI
R. S. Shorter1
TL;DR: The principles of adaptive optics, 3rd edn., by Robert K. Tyson, Abingdon, CRC Press, 2010, 314 pp., £57.99 (hardback), ISBN 978-143980858080 as discussed by the authors.
Abstract: Principles of Adaptive Optics, 3rd edn., by Robert K. Tyson, Abingdon, CRC Press, 2010, 314 pp., £57.99 (hardback), ISBN 978-1439808580. Scope: reference. Level: postgraduate. Bob Tyson came in on ...

Journal ArticleDOI
TL;DR: A review of the current state of research on super-Earths, and models of the formation, dynamical evolution, and possible habitability of these objects is presented in this paper.
Abstract: Super-Earths, a class of planetary bodies with masses ranging from a few Earth-masses to slightly smaller than Uranus, have recently found a special place in exoplanetary science. Being slightly larger than a typical terrestrial planet, super-Earths may have physical and dynamical characteristics similar to those of Earth whereas unlike terrestrial planets, they are relatively easier to detect. Because of their sizes, super-Earths can maintain moderate atmospheres and possibly dynamic interiors with plate tectonics. They also seem to be more common around low-mass stars where the habitable zone is in closer distances. This article presents a review of the current state of research on super-Earths, and discusses the models of the formation, dynamical evolution, and possible habitability of these objects. Given the recent advances in detection techniques, the detectability of super-Earths is also discussed, and a review of the prospects of their detection in the habitable zones of low-mass stars is presented.

Journal ArticleDOI
Matt Probert1
TL;DR: The Electronic Structure: Basic Theory and Practical Methods, by Richard M. Martin, Cambridge, Cambridge University Press, 2004, 648 pp., £49.00 (hardback), ISBN 978-0521782852.
Abstract: Electronic Structure: Basic Theory and Practical Methods, by Richard M. Martin, Cambridge, Cambridge University Press, 2004, 648 pp., £49.00 (hardback), ISBN 978-0521782852. Scope: graduate level t...

Journal ArticleDOI
TL;DR: In this article, the applicability of some physical models to olfaction and look in particular at one theory within the realm of olfactory science is discussed. But it is based on a form of Inelastic Electron Tunnelling (IETS).
Abstract: Smell is a physical process used by us all, but fully understood by none. A physicist seeks to understand the mysterious phenomena of nature and so it is natural to apply physics to this problem. There is a reluctance in the field of olfactory science to explore the physical processes of fundamental interactions in odorant recognition because the system is complex. However, nature is often compliant to our simple models, and part of the art is to reduce the problem to a soluble one, and part of the beauty of science is often that the simple model with the simple answers give the right ones. This article reviews the applicability of some physical models to olfaction and looks in particular at one theory within the realm of olfactory science. This theory was first endorsed by Turin in 1996, that smell signalling may be based on a form of Inelastic Electron Tunnelling (IETS). This review looks at the mystery of olfaction and the physical principles that may unveil such mysterious phenomena.

Journal ArticleDOI
TL;DR: An Introduction to the Theory of Stellar Structure and Evolution, 2nd edn., by Dina Prialnik, Cambridge, Cambridge University Press, 2009, 330 pp., £37.00 (hardback), ISBN 978-0-521-86604-0 as mentioned in this paper.
Abstract: An Introduction to the Theory of Stellar Structure and Evolution, 2nd edn., by Dina Prialnik, Cambridge, Cambridge University Press, 2009, 330 pp., £37.00 (hardback), ISBN 978-0-521-86604-0. Scope:...

Journal ArticleDOI
TL;DR: Ni and I.L.Chuang, 2010, 708 pp., £45.00 (hardback), ISBN 978-1-107-00217-3 as discussed by the authors...
Abstract: Quantum Computation and Quantum Information, by M.A. Nielsen and I.L. Chuang, Cambridge, Cambridge University Press, 2010, 708 pp., £45.00 (hardback), ISBN 978-1-107-00217-3. Scope: textbook. Level...

Journal ArticleDOI
TL;DR: In this paper, the authors present an overview of the dynamical phenomena exhibited by genetic circuits and their functional significance, and describe the theoretical and experimental approaches that are being used to unravel the relationship between circuit structure and function in dynamical cellular processes under the influence of noise.
Abstract: Cellular behaviour is governed by gene regulatory processes that are intrinsically dynamic and nonlinear, and are subject to non-negligible amounts of random fluctuations. Such conditions are ubiquitous in physical systems, where they have been studied for decades using the tools of statistical and nonlinear physics. The goal of this introductory tutorial is to show how approaches traditionally used in physics can help in reaching a systems-level understanding of living cells. To that end, we present an overview of the dynamical phenomena exhibited by genetic circuits and their functional significance. We also describe the theoretical and experimental approaches that are being used to unravel the relationship between circuit structure and function in dynamical cellular processes under the influence ofnoise. Studies are discussed both at the single-cell level and in cellular populations, where intercellular coupling plays an important role.

Journal ArticleDOI
TL;DR: An overview of the use of radio waves in archaeology is presented, first introducing the main physical concepts of GPR, then presenting some examples of its application to detect ancient buried structures, showing the potential and the... as discussed by the authors.
Abstract: Geophysical techniques can be effectively applied to produce an image of buried targets in a host medium, through the detection of the ‘boundaries’ between materials having different values of a specific physical property. Over the last 30 years these methods have been increasingly used to detect the presence of archaeological ruins in the subsurface, thus reducing extensive, destructive, time consuming and expensive excavations. Recently, ground penetrating radar (GPR) has become the most important physical technique in archaeological investigations (allowing for the detection of archaeological targets with both very high vertical and horizontal resolution) and has been successfully applied also to diagnostic purposes in historical buildings and monuments. In this article an overview of the use of radio waves in archaeology is presented, first introducing the main physical concepts of GPR, then presenting some examples of its application to detect ancient buried structures, showing the potential and the ...

Journal ArticleDOI
TL;DR: In this paper, a review of the various technologies used to accelerate charged particles to high energies is presented, focusing on the way in which different technologies are used together to convey energy from the electrical supply to the accelerated particles.
Abstract: Particle accelerators have many important uses in scientific experiments, in industry and in medicine. This paper reviews the variety of technologies which are used to accelerate charged particles to high energies. It aims to show how the capabilities and limitations of these technologies are related to underlying physical principles. The paper emphasises the way in which different technologies are used together to convey energy from the electrical supply to the accelerated particles.

Journal ArticleDOI
TL;DR: The nuclear shell model is a benchmark for the description of the structure of atomic nuclei and it has important implications for the synthesis of heavy elements in stars and stellar explosions as mentioned in this paper.
Abstract: The nuclear shell model is a benchmark for the description of the structure of atomic nuclei. The magic numbers associated with closed shells have long been assumed to be valid across the whole nuclear chart. Investigations in recent years of nuclei far away from nuclear stability at facilities for radioactive ion beams have revealed that the magic numbers may change locally in those exotic nuclei leading to the disappearance of classic shell gaps and the appearance of new magic numbers. These changes in shell structure also have important implications for the synthesis of heavy elements in stars and stellar explosions. In this review a brief overview of the basics of the nuclear shell model will be given together with a summary of recent theoretical and experimental activities investigating these changes in the nuclear shell structure.

Journal ArticleDOI
TL;DR: Quantum Mechanics: Concepts and Applications, 2nd edn., by Nouredine Zettili, Chichester, Wiley, 2009, 686 pp., £39.95 (paperback), ISBN 978-0-470-02679-3.
Abstract: Quantum Mechanics: Concepts and Applications, 2nd edn., by Nouredine Zettili, Chichester, Wiley, 2009, 686 pp., £39.95 (paperback), ISBN 978-0-470-02679-3. Scope: textbook. Level: undergraduates an...

Journal ArticleDOI
TL;DR: In this article, the authors consider a new viewpoint to study the dynamics of chaotic and non-linear systems using black hole dynamics, and propose a geometrical framework for studying these features, called geometrisation of turbulence.
Abstract: The dynamics of fluids is a long standing challenge that remained as an unsolved problem for centuries. Understanding its main features, chaos and turbulence, is likely to provide an understanding of the principles and non-linear dynamics of a large class of systems far from equilibrium. We consider a conceptually new viewpoint to study these features using black hole dynamics. Since the gravitational field is characterised by a curved geometry, the gravity variables provide a geometrical framework for studying the dynamics of fluids: a geometrisation of turbulence.

Journal ArticleDOI
TL;DR: In this paper, N.N. Bogolubov et al. introduce the concept of quantum statistical mechanics and propose an introduction to Quantum Statistical Mechanics, 2nd edn.
Abstract: Introduction to Quantum Statistical Mechanics, 2nd edn., by N.N. Bogolubov and N.N. Bogolubov Jr., Singapore, World Scientific, 2009, 440 pp., £60.00 (hardback), ISBN 978-9-814-29519-2. Scope: mono...

Journal ArticleDOI
TL;DR: Seager et al. as mentioned in this paper described the physical processes of the exoplanet atmosphere and its physical processes, including the formation, evolution, and cooling of the Earth's magnetic field.
Abstract: Exoplanet Atmospheres: Physical Processes, by Sara Seager, Princeton, Princeton University Press, 2010, 264 pp, £3095 (hardback), ISBN 978-0-691-14645-4 Scope: reference Level: postgraduate, ea

Journal ArticleDOI
TL;DR: In the summer of 1961, a landmark experiment was performed at the University of Michigan in which optical second harmonic generation was observed for the first time as discussed by the authors, and this event 50 years ago marked the birth of modern nonlinear optics.
Abstract: In the summer of 1961, a landmark experiment was performed at the University of Michigan in which optical second harmonic generation was observed for the first time. This event 50 years ago marked the birth of modern nonlinear optics, and this article celebrates the first half century of what is now a vast and vibrant field at the cutting edge of laser technology. The focus is mainly on nonlinear optics in the 1960s partly because it is appropriate in this anniversary year to remember the genesis of the field, but also because such remarkable progress was made in the first few years. However, a brief review of where things stand at present is included, and one aspect of the field today (high harmonic generation) is taken as a representative example of an area of nonlinear optics that lies at the current frontier of knowledge.