A microscopic view of the Fourier law
Publication date: Available online 19 September 2019Source: Comptes Rendus PhysiqueAuthor(s): Thierry Bodineau, Isabelle Gallagher, Laure Saint-RaymondAbstractThe Fourier law of heat conduction describes heat diffusion in macroscopic systems. This physical law has been experimentally tested for a large class of physical systems. A natural question is to know whether it can be derived from the microscopic models using the fundamental laws of mechanics.RésuméLa loi de Fourier permet de décrire la diffusion de la chaleur dans des systèmes physiques à l'échelle macroscopique. Cette loi est très bien vérifiée expérime...
Source: Comptes Rendus Physique - September 20, 2019 Category: Physics Source Type: research
From space-time chaos to stochastic thermodynamics
We describe experiments where all these concepts have been applied and tested with high accuracy. Finally, we show how these theoretical concepts and the experiments allowed us to improve our knowledge on the connection between information and thermodynamics.RésuméNous résumons plusieurs expériences qui montrent l'évolution de certains intérêts et objectifs scientifiques de la physique statistique au cours des quarante dernières années. En particulier, nous présentons de quelle façon les idées sur les fluctuations d'énergie dans les systèmes hors équilibre se sont développées aux niveaux théorique et exp...
Source: Comptes Rendus Physique - September 20, 2019 Category: Physics Source Type: research
Fourier's law based on microscopic dynamics
We report on recent, and not so recent, advances.RésuméBien que la loi de Fourier soit confirmée empiriquement pour de nombreuses substances et sur un très large domaine de paramètres thermodynamiques, une dérivation microscopique convaincante pose encore des difficultés. Avec les machines actuelles, la solution des équations de mouvement de Newton peut être obtenues avec une grande précision et pour un nombre raisonnablement grand de particules. Pour les systèmes modèles simplifiés, on parvient ainsi à une compréhension plus approfondie de la base microscopique de la loi de Fourier. Nous discutons les progr...
Source: Comptes Rendus Physique - September 20, 2019 Category: Physics Source Type: research
Fourier could be a data scientist: From graph Fourier transform to signal processing on graphs
Publication date: Available online 19 September 2019Source: Comptes Rendus PhysiqueAuthor(s): Benjamin Ricaud, Pierre Borgnat, Nicolas Tremblay, Paulo Gonçalves, Pierre VandergheynstAbstractThe legacy of Joseph Fourier in science is vast, especially thanks to the essential tool that the Fourier transform is. The flexibility of this analysis, its computational efficiency and the physical interpretation it offers makes it a cornerstone in many scientific domains. With the explosion of digital data, both in quantity and diversity, the generalization of the tools based on Fourier transform is mandatory. In data science, new p...
Source: Comptes Rendus Physique - September 20, 2019 Category: Physics Source Type: research
Editorial Board
Publication date: May–June 2019Source: Comptes Rendus Physique, Volume 20, Issue 4Author(s): (Source: Comptes Rendus Physique)
Source: Comptes Rendus Physique - September 16, 2019 Category: Physics Source Type: research
Dossier Sommaire
Publication date: May–June 2019Source: Comptes Rendus Physique, Volume 20, Issue 4Author(s): (Source: Comptes Rendus Physique)
Source: Comptes Rendus Physique - September 16, 2019 Category: Physics Source Type: research
Editorial Board
Publication date: May–June 2019Source: Comptes Rendus Physique, Volume 20, Issue 4Author(s): (Source: Comptes Rendus Physique)
Source: Comptes Rendus Physique - September 16, 2019 Category: Physics Source Type: research
Role of conserved quantities in Fourier's law for diffusive mechanical systems
Publication date: Available online 10 September 2019Source: Comptes Rendus PhysiqueAuthor(s): Stefano OllaAbstractEnergy transport can be influenced by the presence of other conserved quantities. We consider here diffusive systems where energy and the other conserved quantities evolve macroscopically on the same diffusive space–time scale. In these situations, the Fourier law depends also on the gradient of the other conserved quantities. The rotor chain is a classical example of such systems, where energy and angular momentum are conserved. We review here some recent mathematical results about the diffusive transport of...
Source: Comptes Rendus Physique - September 11, 2019 Category: Physics Source Type: research
Fourier at the heart of computer music: From harmonic sounds to texture
This article proposes to revisit the scientific legacy of Joseph Fourier through the lens of computer music research. We first discuss how the Fourier series marked a paradigm shift in our understanding of acoustics, supplanting the theory of consonance of harmonics in the Pythagorean monochord. Then, we highlight the utility of Fourier's paradigm via three practical problems in analysis–synthesis: the imitation of musical instruments, frequency transposition, and the generation of audio textures. Interestingly, each of these problems involves a different perspective on time–frequency duality, and stimulates a multidis...
Source: Comptes Rendus Physique - September 7, 2019 Category: Physics Source Type: research
Glassy dynamics in strongly anharmonic chains of oscillators
Publication date: Available online 3 September 2019Source: Comptes Rendus PhysiqueAuthor(s): Wojciech De Roeck, François HuveneersAbstractWe review the mechanism for transport in strongly anharmonic chains of oscillators near the atomic limit where all oscillators are decoupled. In this regime, the motion of most oscillators remains close to integrable, i.e. quasi-periodic, on very long time scales, while a few chaotic spots move very slowly and redistribute the energy across the system. The material acquires several characteristic properties of dynamical glasses: intermittency, jamming, and a drastic reduction of the mob...
Source: Comptes Rendus Physique - September 4, 2019 Category: Physics Source Type: research
Fourier's law and many-body quantum systems
Publication date: Available online 3 September 2019Source: Comptes Rendus PhysiqueAuthor(s): Christian B. MendlAbstractThe topic of this article are transport properties of many-body quantum chains accompanying DMRG-type simulations of the Bose–Hubbard model. To set the stage, we first provide a very brief introduction to many-body quantum theory and tensor network approximations. Transport properties are studied via dynamical density correlation functions, in line with linear response theory. We observe diffusive behavior at “infinite temperature” T→∞. Finally, we mention other approaches to study transport, e.g...
Source: Comptes Rendus Physique - September 4, 2019 Category: Physics Source Type: research
Les débuts du laboratoire Pierre-Aigrain
We describe the birth and growth of the Solid State laboratory at “École normale supérieure”, Paris. The director of the Physics Department, Yves Rocard, understood the importance of semiconductors for the future of electronics and recruited a young Frenchman, Pierre Aigrain, who had just received a PhD from Carnegie Tech. The first domains explored proved to be very important for future applications: optical properties, transport properties, new semiconductor compounds. Later new fields were developed such as superconductors, tunnel effect spectroscopy, turbulence and chaos in hydrodynamics, properties of superfluid...
Source: Comptes Rendus Physique - August 22, 2019 Category: Physics Source Type: research
Louis Néel: His multifaceted seminal work in magnetism
Publication date: Available online 14 August 2019Source: Comptes Rendus PhysiqueAuthor(s): Bernard BarbaraAbstractLouis Néel was a world-renowned scientist who devoted the research part of his multi-faceted career to magnetism. Covering roughly the period 1930–1970, his work is explained for a non-specialized audience, with particular attention given to work published in the Comptes rendus hebdomadaires des séances de l'Académie des sciences.RésuméLouis Néel fut un savant de réputation mondiale. De ses activités multiples, celle consacrée à la recherche concerne principalement le magnétisme. Elle s'étend de 1...
Source: Comptes Rendus Physique - August 16, 2019 Category: Physics Source Type: research
Des premiers lasers à gaz carbonique aux interféromètres atomiques et moléculaires
The objective of this publication is to bring out the common thread that has guided me on a sometimes chaotic path from spectroscopy to atomic interferometry. The search for an ever-increasing resolving power has led spectroscopists to take into account the external motion of atoms and molecules. The usual Doppler broadening and then the relativistic Doppler effect could be accommodated with a classical treatment of this external motion. But the recoil effect has required to introduce explicitly momentum conservation between light and atoms. This has imposed to treat simultaneously internal and external degrees of freedom ...
Source: Comptes Rendus Physique - August 7, 2019 Category: Physics Source Type: research
Magnetic structures
Publication date: Available online 26 July 2019Source: Comptes Rendus PhysiqueAuthor(s): Juan Rodríguez-Carvajal, Jacques VillainAbstractWhile ferromagnetism has been known since many centuries, more complex magnetic structures have only been identified in the twentieth century: ferrimagnetism, antiferromagnetism, helimagnetism, modulated structures… Incommensurable or long-period structures have first been deduced as consequences of phenomenological models, e.g., the Heisenberg Hamiltonian. The more fundamental explanation of Rudermann, Kittel, Kasuya, and Yoshida relies on the general phenomenon of Friedel oscillation...
Source: Comptes Rendus Physique - July 28, 2019 Category: Physics Source Type: research
