Metamaterials and invisibility

Metamaterials have significantly extended the range of electromagnetic properties available to device designers. An interesting application of these new materials is to the problem of cloaking, where the goal is to render an object invisible to electromagnetic radiation within a certain frequency range. Here, I review the concepts behind recently-proposed invisibility cloaks, and the way in which metamaterials can allow these designs to be realized. To cite this article: B. Wood, C. R. Physique 10 (2009).     

Higher spin gauge theories in any dimension

Some general properties of higher spin gauge theories are summarized, with the emphasize on the nonlinear theories in any dimension. To cite this article: M.A. Vasiliev, C. R. Physique 5 (2004).

Résumé

Des propriétés générales des théories de jauge de grands spins sont présentées, en insistant particulièrement sur les théories non-linéaires en dimensions diverses. Pour citer cet article : M.A. Vasiliev, C. R. Physique 5 (2004).     

Variations on the warped deformed conifold

The warped deformed conifold background of type IIB theory is dual to the cascading SU(M(p+1))×SU(Mp) gauge theory. We show that this background realizes the (super-)Goldstone mechanism where the U(1) baryon number symmetry is broken by expectation values of baryonic operators. The resulting massless pseudo-scalar and scalar glueballs are identified in the supergravity spectrum. A D-string is then dual to a global string in the gauge theory. Upon compactification, the Goldstone mechanism turns into the Higgs mechanism, and the global strings turn into ANO strings. To cite this article: S.S. Gubser et al., C. R. Physique 5 (2004).

Résumé

La configuration de fond pour la théorie de type IIB donnée par le conifold voilé déformé est duale à la cascade de théorie de jauge SU(M(p+1))×SU(Mp). Nous montrons que cette configuration donne une réalisation du mécanisme de (super-)Goldstone où la symètrie baryonique U(1) est brisée par la valeur moyenne dans le vide des opérateurs baryoniques. Les boules de glue pseudo-scalaires et scalaires de masse nulle résultantes sont identifiées dans le spectre de supegravité. Une D-corde est alors duale à une corde globale dans la théorie de jauge. Après compactification, le mécanisme de Goldstone devient un mécanisme de Higgs, et une corde globale devient une corde ANO. Pour citer cet article : S.S. Gubser et al., C. R. Physique 5 (2004).     

Cloaking by plasmonic resonance among systems of particles: cooperation or combat?

We study quasistatic cloaking by the mechanism of plasmonic resonance, for systems of coated cylinders. Our focus is on the nature of the resonant cloaking interaction: whether systems of particles can be made to cooperate in cloaking a polarizable particle from an applied uniform field. We show that in fact if the cloaking regions of the systems of particles overlap, then they tend to interact in a fashion detrimental to their cloaking of the polarizable particle. If the cloaking regions touch but do not overlap, then the system of particles can cloak a larger region than each would in isolation. To cite this article: R.C. McPhedran et al., C. R. Physique 10 (2009).     

Atomic modeling of irradiation-induced hardening

We review recent results obtained by Molecular Dynamics (MD) simulations on the elementary interaction mechanisms between dislocations and irradiation defects, with the aim to obtain a fundamental understanding of plasticity in irradiated metals. The reactions obtained included defect shear, drag and absorption in edge and screw dislocations. We present the state of the art in both FCC and BCC metals and discuss the challenges faced by MD simulations, in particular in BCC metals in order to realistically simulate the thermally-activated glide of screw dislocations in the presence of obstacles. To cite this article: D. Rodney, C. R. Physique 9 (2008).     

Basic results in vacuum statistics

This is a review of recent work on constructing and finding statistics of string theory vacua, done in collaboration with Frederik Denef, Bogdan Florea, Bernard Shiffman and Steve Zelditch. To cite this article: M.R. Douglas, C. R. Physique 5 (2004).

Résumé

Cet article est une revue de travaux récents sur la construction et découverte de statistiques des vides de théories des cordes, réalisée en collaboration avec Frederik Denef, Bogdan Florea, Bernard Shiffman et Steve Zelditch. Pour citer cet article : M.R. Douglas, C. R. Physique 5 (2004).     

Modelling of long term kinetic evolution: a fruitful relationship between experiment and theoretical development

Recent developments in multi-scale modelling, based on atomic scale calculations, are leading to a growing conviction that modelling will soon be used to design material components for nuclear reactors. In this article we discuss this assumption on the basis of the relationship between experimental studies and theoretical calculations of the microstructural evolution of materials under irradiation. In the first part of the paper, the available numerical models for long term microstructural evolutions are briefly reviewed. The experimental methods are presented in a second part. In the third part, several examples of fruitful relationships between modelling and experiments are discussed. To cite this article: A. Barbu, C. R. Physique 9 (2008).     

Holographic dynamics of unstable branes in AdS

The gauge theory dual to the decay of an unstable D-particle in AdS is analysed in terms of coherent states. We discuss in detail how to count the number of particles in the decay product. We find, in agreement with the analysis in flat space, that the emission amplitude is suppressed as the mass of the radiated particles increases. To cite this article: M. Zamaklar, K. Peeters, C. R. Physique 5 (2004).

Résumé

La théorie de jauge duale à la désintégration de D-particules instables dans AdS est analysée en termes d'état cohérents. Nous discutons en détails le comptage du nombre de particule dans le produit de désintégration. Nous trouvons, en accord avec l'analyse en espace plat, que le taux d'émission est supprimé quand la masse de la particule augmente. Pour citer cet article : M. Zamaklar, K. Peeters, C. R. Physique 5 (2004).     

Cavitation in water: a review

Liquid water can be brought beyond the liquid–vapor equilibrium line into a metastable state, before nucleation of bubbles (cavitation) occurs. We review the experimental work on cavitation in water, focusing on the determination of the ultimate degree of metastability at which liquid water can exist. We also present practical applications of metastability and cavitation. To cite this article: F. Caupin, E. Herbert, C. R. Physique 7 (2006).     

Nucleation problems in metallurgy of the solid state: recent developments and open questions

Nucleation processes play a key role in the microstructure evolution of metallic alloys during thermomechanical treatments. These processes can involve phase transformations (such as precipitation) and structural instabilities (such as recrystallisation). Although the word ‘nucleation’ is used in both cases, the situation is profoundly different for precipitation and for recrystallisation on which this article is focussed. In the case of precipitation, species are conserved and the underlying physics is stochastic fluctuations, allowing the apparition of critical germs of the new phase. In the case of recrystallisation, the underlying physical phenomenon is the progressive growth of subgrain structures leading to an unstable configuration, allowing a dislocation free grain to grow at the expense of a dislocated one. The two cases require different types of modelling which are presented in the article. To cite this article: Y. Bréchet, G. Martin, C. R. Physique 7 (2006).     

A review of X-ray intensity fluctuation spectroscopy

This article reviews the literature on X-ray fluctuation intensity spectroscopy or, as it is often called, X-ray photon correlation spectroscopy. It highlights measurements using different types of diffuse scattering. To cite this article: M. Sutton, C. R. Physique 9 (2008).     

X-ray detected optical activity

Optical Activity (OA) was only measured quite recently in the X-ray range using electric dipole–electric quadrupole interference terms that mix multipoles of opposite parity but are only present in systems with broken inversion symmetry. Natural OA refers to effects that are even with respect to time-reversal symmetry, whereas non-reciprocal OA is concerned with time-reversal odd contributions. Various types of X-ray dichroism related to either natural or non-reciprocal OA have been detected and are reviewed in the present paper. To cite this article: A. Rogalev et al., C. R. Physique 9 (2008).     

Supersymmetric backgrounds from generalized Calabi–Yau manifolds

We show that the supersymmetry transformations for type II string theories on six-manifolds can be written as differential conditions on a pair of pure spinors, the exponentiated Kähler form e^iJ and the holomorphic form Ω. The equations are explicitly symmetric under exchange of the two pure spinors and a choice of even or odd-rank RR field. This is mirror symmetry for manifolds with torsion. Moreover, RR fluxes affect only one of the two equations: e^iJ is closed under the action of the twisted exterior derivative in IIA theory, and similarly Ω is closed in IIB. This means that supersymmetric SU(3)-structure manifolds are always complex in IIB while they are twisted symplectic in IIA. Modulo a different action of the B-field, these are all generalized Calabi–Yau manifolds, as defined by Hitchin. To cite this article: M. Graña et al., C. R. Physique 5 (2004).

Résumé

On montre que les transformations de supersymétrie pour les théories des cordes de type II peuvent être traduites dans des équations différentielles pour une paire de spineurs purs, l'exponentiel de la forme de Kähler e^iJ et la forme holomorphe Ω. Ces équations sont symétriques sous l'échange des deux spineurs purs et des formes de RR de rang pair ou impair. Cette propriété est la symétrie miroir pour les variétés avec torsion. On voit aussi que les fluxes de RR entrent seulement dans une des deux équations : e^iJ est fermé sous l'action de la dérivée extérieure « twisted » dans la corde de type IIA, et de la même manière Ω est fermé en type IIB. Cela implique que les variétés supersymétriques de structure SU(3) sont toujours complexes en type IIB ou bien symplectiques « twisted » en IIA. Ces variétés sont donc des variétés des Calabi–Yau généralisées selon la définition de Hitchin, mais avec une action du champ B différente. Pour citer cet article : M. Graña et al., C. R. Physique 5 (2004).     

Hard X-ray PhotoEmission Spectroscopy of strongly correlated systems

Hard X-ray PhotoEmission Spectroscopy (HAXPES) is a new tool for the study of bulk electronic properties of solids using synchrotron radiation. We review recent achievements of HAXPES, with particular reference to the VOLPE project, showing that high energy resolution and bulk sensitivity can be obtained at kinetic energies of 6–8 keV. We present also the results of recent studies on strongly correlated materials, such as vanadium sesquioxide and bilayered manganites, revealing the presence of different screening properties in the bulk with respect to the surface. We discuss the relevant experimental features of the metal–insulator transition in these materials. To cite this article: G. Panaccione et al., C. R. Physique 9 (2008).     

Resonant Inelastic X-ray Scattering: From band mapping to inter-orbital excitations

Resonant inelastic X-ray scattering (also known as resonant X-ray Raman spectroscopy when only valence and conduction states are involved in the final state excitation) has developed into a major tool for understanding the electronic properties of complex materials. Presently it provides access to electron excitations in the few hundred meV range with element and bulk selectivity. Recent progress in X-ray optics and synchrotron radiation engineering have opened up new perspectives for this powerful technique to improve resolving power and efficiency. We briefly present the basics of the method and illustrate its potential with examples chosen from the literature. To cite this article: J. Lüning, C.F. Hague, C. R. Physique 9 (2008).     

Specific architectures for optical parametric oscillators

Optical parametric oscillators are coherent light sources showing properties that are not encountered with usual laser sources. This article deals with optical architectures that take advantage of the specific properties of the three-wave mixing parametric interaction. We show that optical cavities can be specifically designed to increase either the optical conversion of the parametric process or to reduce dramatically the emitted line width. To cite this article: A. Berrou et al., C. R. Physique 8 (2007).     

Fresnel phase matching: a universal phase matching scheme

We present new theoretical concepts for Fresnel phase matching. A guided wave approach is described, which allows us to intrinsically take into account all the physical processes involved. To cite this article: M. Raybaut et al., C. R. Physique 8 (2007).     

High-resolution inelastic x-ray scattering to study the high-frequency atomic dynamics of disordered systems

The use of momentum-resolved inelastic x-ray scattering with meV energy resolution to study the high-frequency atomic dynamics in disordered systems is here reviewed. The typical realization of this experiment is described together with some common models used to interpret the measured spectra and to extract parameters of interest for the investigation of disordered systems. With the help of some selected examples, the present status of the field is discussed. Particular attention is given to those results which are still open for discussion or controversial, and which will require further development of the technique to be fully solved. Such an instrumental development seems nowadays possible at the light of recently proposed schemes for advanced inelastic x-ray scattering spectrometers. To cite this article: G. Monaco, C. R. Physique 9 (2008).     

Nuclear resonance scattering

Nuclear resonance scattering is an atomistic spectroscopy sensitive to magnetic and electronic properties as well as slow and fast structural dynamics. Applications, which take advantage of both the outstanding properties of third generation synchrotron radiation sources and those of the Mössbauer effect, benefit most. Examples resulting from investigations at the ESRF will be given in applications to high pressure and low temperatures, nano-scale materials, and dynamics of disordered systems. To cite this article: R. Rüffer, C. R. Physique 9 (2008).     

AC transport in carbon-based devices: challenges and perspectives

Time-dependent fields are a valuable tool to control fundamental quantum phenomena in highly coherent low dimensional electron systems. Carbon nanotubes and graphene are a promising ground for these studies. Here we offer a brief overview of driven electronic transport in carbon-based materials with the main focus on carbon nanotubes. Recent results predicting control of the current and noise in nanotube based Fabry–Pérot devices are highlighted. To cite this article: L.E.F. Foa Torres, G. Cuniberti, C. R. Physique 10 (2009).