Chalcogenide microstructured optical fibres for mid-IR applications
Publication date: Available online 24 November 2016 Source:Comptes Rendus Physique Author(s): Johann Trolès, Laurent Brilland Compared to oxide-based glasses, vitreous materials composed of chalcogen elements (S, Se, Te) show large transparency windows in the infrared. Indeed, chalcogenide glasses can be transparent from the visible up to 12 – 18 μm , depending on their compositions. In addition, chalcogenide glasses contain large polarisable atoms and external lone electron pairs that induce exceptional non-linear properties. Consequently, the non-linear properties can be 100 or 1000 times as high as the non-li...
Source: Comptes Rendus Physique - November 23, 2016 Category: Physics Source Type: research
Geometric aspects of ordering phenomena
Publication date: Available online 16 November 2016 Source:Comptes Rendus Physique Author(s): Leticia F. Cugliandolo A macroscopic system prepared in a disordered phase and quenched across a second-order phase transition into an ordered phase undergoes a coarsening process whereby it orders locally in one of the equilibrium states. The study of the evolution of the morphology of the ordered structures in two dimensions has recently unveiled two interesting and generic features. On the one hand, the dynamics first approach a critical percolating state via the growth of a new lengthscale and satisfying scaling properties ...
Source: Comptes Rendus Physique - November 16, 2016 Category: Physics Source Type: research
Quantum simulation of disordered systems with cold atoms
Publication date: Available online 13 October 2016 Source:Comptes Rendus Physique Author(s): Jean-Claude Garreau This paper reviews the physics of quantum disorder in relation with a series of experiments using laser-cooled atoms exposed to “kicks” of a standing wave, realizing a paradigmatic model of quantum chaos, the kicked rotor. This dynamical system can be mapped onto a tight-binding Hamiltonian with pseudo-disorder, formally equivalent to the Anderson model of quantum disorder, with quantum chaos playing the role of disorder. This provides a very good quantum simulator for the Anderson physics. (Source: Comptes Rendus Physique)
Source: Comptes Rendus Physique - October 13, 2016 Category: Physics Source Type: research
Thermoelectric transport and Peltier cooling of cold atomic gases
Publication date: Available online 19 September 2016 Source:Comptes Rendus Physique Author(s): Charles Grenier, Corinna Kollath, Antoine Georges This brief review presents the emerging field of mesoscopic physics with cold atoms, with an emphasis on thermal and ‘thermoelectric’ transport, i.e. coupled transport of particles and entropy. We review in particular the comparison between theoretically predicted and experimentally observed thermoelectric effects in such systems. We also show how combining well-designed transport properties and evaporative cooling leads to an equivalent of the Peltier effect with cold at...
Source: Comptes Rendus Physique - September 19, 2016 Category: Physics Source Type: research
Star formation and chemical complexity in the Orion nebula: A new view with the IRAM and ALMA interferometers
Publication date: Available online 16 September 2016 Source:Comptes Rendus Physique Author(s): Alain Baudry, Nathalie Brouillet, Didier Despois The Orion nebula is one of the most observed celestial regions in the Milky Way. It is an active massive star-forming region, especially well studied in the millimeter and submillimeter domains that allow us to unveil the cool and obscured regions in which stars are being formed. After a brief introduction to the main properties of a radio telescope, we recall that the most sensitive radio interferometers, the IRAM mm array and, especially, the recently built ALMA millimeter/s...
Source: Comptes Rendus Physique - September 16, 2016 Category: Physics Source Type: research
A variety of radars designed to explore the hidden structures and properties of the Solar System's planets and bodies
Publication date: Available online 15 September 2016 Source:Comptes Rendus Physique Author(s): Valérie Ciarletti Since the very first observations of the Moon from the Earth with radar in 1946, radars are more and more frequently selected to be part of the payload of exploration missions in the Solar System. They are, in fact, able to collect information on the surface structure of bodies or planets hidden by opaque atmospheres, to probe the planet subsurface or even to reveal the internal structure of a small body comet nucleus. A brief review of radars designed for the Solar System planets and bodies' exploration is ...
Source: Comptes Rendus Physique - September 15, 2016 Category: Physics Source Type: research
Nanostructuration for thermoelectricity: The path to an unlimited reduction of phonon transport
Publication date: Available online 15 September 2016 Source:Comptes Rendus Physique Author(s): Shiyun Xiong, Sebastian Volz Improvements of the thermoelectric properties in bulk materials have very often relied on the reduction of thermal conductivity, which is mostly based on phonon propagation. Reducing further phonon transport has remained a difficult task due to the fact that current thermoelectric materials are already efficient thermal insulators, and also because of the broadness of the Planckian phonon spectrum. Nanostructuring has provided new paths for decreasing thermal conduction, especially by means of sca...
Source: Comptes Rendus Physique - September 15, 2016 Category: Physics Source Type: research
Experiments on the thermoelectric properties of quantum dots
Publication date: Available online 29 August 2016 Source:Comptes Rendus Physique Author(s): Artis Svilans, Martin Leijnse, Heiner Linke Quantum dots (QDs) are good model systems for fundamental studies of mesoscopic transport phenomena using thermoelectric effects because of their small size, electrostatically tunable properties and thermoelectric response characteristics that are very sensitive to small thermal biases. Here we provide a review of experimental studies on thermoelectric properties of single QDs realized in two-dimensional electron gases, single-walled carbon nanotubes and semiconductor nanowires. A key...
Source: Comptes Rendus Physique - August 29, 2016 Category: Physics Source Type: research
A new technique to characterize foliage attenuation using passive radar in the L-band
Publication date: Available online 27 August 2016 Source:Comptes Rendus Physique Author(s): Marc Lesturgie, Laetitia Thirion-Lefèvre, Stéphane Saillant, Philippe Dorey The goal of the experiment proposed in this paper is to give rapidly and with a limited equipment the attenuation level in the L-band for various elevation angles, between 20 and 70 degrees. The original principle is to use the L-band signal transmitted from an airport radar. The signal backscattered by a plane flying over the forest next to the airport is received on many antennas: some are over the canopy; others are on the ground under the foliage...
Source: Comptes Rendus Physique - August 26, 2016 Category: Physics Source Type: research
Exciton-polaritons in lattices: A non-linear photonic simulator
Publication date: Available online 25 August 2016 Source:Comptes Rendus Physique Author(s): Alberto Amo, Jacqueline Bloch Microcavity polaritons are mixed light–matter quasiparticles with extraordinary nonlinear properties, which can be easily accessed in photoluminescence experiments. Thanks to the possibility of designing the potential landscape of polaritons, this system provides a versatile photonic platform to emulate 1D and 2D Hamiltonians. Polaritons allow transposing to the photonic world some of the properties of electrons in solid-state systems, and to engineer Hamiltonians for photons with novel transport ...
Source: Comptes Rendus Physique - August 25, 2016 Category: Physics Source Type: research
Linear and nonlinear mesoscopic thermoelectric transport with coupling with heat baths
Publication date: Available online 25 August 2016 Source:Comptes Rendus Physique Author(s): Jian-Hua Jiang, Yoseph Imry Decades of research on thermoelectrics stimulated by the fact that nano- and meso-scale thermoelectric transport could yield higher energy conversion efficiency and output power has recently uncovered a new direction on inelastic thermoelectric effects. We introduce the history, motivation, and perspectives on mesoscopic inelastic thermoelectric effects. (Source: Comptes Rendus Physique)
Source: Comptes Rendus Physique - August 25, 2016 Category: Physics Source Type: research
Nonlinear phenomena in quantum thermoelectrics and heat
Publication date: Available online 24 August 2016 Source:Comptes Rendus Physique Author(s): David Sánchez, Rosa López We review recent developments in nonlinear quantum transport through nanostructures and mesoscopic systems driven by thermal gradients or in combination with voltage biases. Low-dimensional conductors are excellent platforms for analyzing both the thermoelectric and heat dynamics beyond the linear response because, due to their small size, a small temperature difference applied across regions gives rise to large thermal biases. We offer a theoretical discussion based on the scattering approach to high...
Source: Comptes Rendus Physique - August 24, 2016 Category: Physics Source Type: research
Reduction of phonon mean free path: From low-temperature physics to room temperature applications in thermoelectricity
Publication date: Available online 23 August 2016 Source:Comptes Rendus Physique Author(s): Olivier Bourgeois, Dimitri Tainoff, Adib Tavakoli, Yanqing Liu, Christophe Blanc, Mustapha Boukhari, André Barski, Emmanuel Hadji It has been proposed for a long time now that the reduction of the thermal conductivity by reducing the phonon mean free path is one of the best way to improve the current performance of thermoelectrics. By measuring the thermal conductance and thermal conductivity of nanowires and thin films, we show different ways of increasing the phonon scattering from low-temperature up to room-temperature...
Source: Comptes Rendus Physique - August 22, 2016 Category: Physics Source Type: research
Thermoelectric and electrical transport in mesoscopic two-dimensional electron gases
Publication date: Available online 21 August 2016 Source:Comptes Rendus Physique Author(s): Vijay Narayan, Michael Pepper, David A. Ritchie We review some of our recent experimental studies on low-carrier concentration, mesoscopic two-dimensional electron gases (m2DEGs). The m2DEGs show a range of striking characteristics, including a complete avoidance of the strongly localised regime even when the electrical resistivity ρ > > h / e 2 , giant thermoelectric response, and an apparent decoupling of charge and thermoelectric transport. We analyse the results and demonstrate that these observations can ...
Source: Comptes Rendus Physique - August 20, 2016 Category: Physics Source Type: research
Maxwell's demons realized in electronic circuits
Publication date: Available online 21 August 2016 Source:Comptes Rendus Physique Author(s): Jonne V. Koski, Jukka P. Pekola We review recent progress in making the former gedanken experiments of Maxwell's demon [1] into real experiments in a lab. In particular, we focus on realizations based on single-electron tunneling in electronic circuits. We first present how stochastic thermodynamics can be investigated in these circuits. Next we review recent experiments on an electron-based Szilard engine. Finally, we report on experiments on single-electron tunneling-based cooling, overviewing the recent realization of a Coulo...
Source: Comptes Rendus Physique - August 20, 2016 Category: Physics Source Type: research
