Giant Collective Spin-Orbit Field in a Quantum Well: Fine Structure of Spin Plasmons

We employ inelastic light scattering with magnetic fields to study intersubband spin plasmons in a quantum well. We demonstrate the existence of a giant collective spin-orbit (SO) field that splits the spin-plasmon spectrum into a triplet. The effect is remarkable as each individual electron would be expected to precess in its own momentum-dependent SO field, leading to D'yakonov-Perel' dephasing. Instead, many-body effects lead to a striking organization of the SO fields at the collective level. The macroscopic spin moment is quantized by a uniform collective SO field, five times higher than the individual SO field. We provide a momentum-space cartography of this field.Comment: 5 pages, 4 figures. Supplemental material available here as an ancillary fil

Dynamical Corrections to Spin Wave Excitations in Quantum Wells due to Coulomb Interactions and Magnetic Ions

We have measured dispersions of spin-flip waves and spin-flip single-particle excitations of a spin polarized two-dimensional electron gas in a CdMnTe quantum well using resonant Raman scattering. We find the energy of the spin-flip wave to be below the spin-flip single particle excitation continuum, a contradiction to the theory of spin waves in diluted magnetic semiconductors put forth in [Phys. Rev. B 70, 045205 (2004)]. We show that the inclusion of terms accounting for the Coulomb interaction between carriers in the spin wave propagator leads to an agreement with our experimental results. The dominant Coulomb contribution leads to an overall red shift of the mixed electron-Mn spin modes while the dynamical coupling between Mn ions results in a small blue shift. We provide a simulated model system which shows the reverse situation but at an extremely large magnetic field.Comment: 6 pages, 7 figure

A new approach for preserving the technical heritage

International audienceAll along history, humans have always invented, created to improve their standard of living. Many machines have been built, sometimes simple and others very complex. In order to achieve the best results for customers, machines, industrial plants and humans are moved, displaced and replaced. It is the global humanity technical knowledge that disappears. Indeed, there is a lack in the actually conservation methods: sciences and technologies have to be considered and not only architecture. Our heritage research focuses on the mechanical and technical point of view. For instance, in a factory, there is the building but also actuators, motors and machines that produce product: taking into account the technical point of view can reach to a better understanding of the past. That's why preserving the national technical patrimony has now become the priority of governments and world organizations. Our approach proposes a new kind of finality: as saving and maintaining physical object cost a lot for museums, and sometimes dismantling is impossible as the machine falls in ruin, we propose to preserve it as a numerical object. The aim of this research is to define the global process and technologies used for implementing a numerical model of old machines. All along the global numerical chain, we will present the different technologies used illustrating them by examples we performed; those examples were experiences realized in France with museums and students in order to sensitize them to a new approach for old technical objects and machines. The global aim is to constitute a new reference for museologic actors, using actual techniques and methods for putting old machines and technical means in “virtual use”, taking into account the working situation including human being at work. From the digitalization of the physical object to its valorization with virtual reality technologies, we present a state of the art of the possibilities offered for creating digital products in a context of technical history and patrimony. According to this inventory, we give the methodology we are developing for preserving technical heritage in a virtual way. This process is illustrated by an example we performed: a steam engine

Knowledge management for industrial heritage

All along history, humans have always invented, created to improve their standard of liv-ing. Many machines have been built, sometimes simple and others very complex. In order to achieve the best results for customers, machines, industrial plants and humans are moved, displaced and replaced. It is the global humanity technical knowledge that dis-appears. Indeed, there is a lack in the actually conservation methods: sciences and technologies have to be considered and not only architecture. Our heritage research focuses on the mechanical and technical point of view. For instance, in a factory, there is the building but also actua-tors, motors and machines that produce product: taking into account the technical point of view can reach to a better understanding of the past. That's why preserving the national technical patrimony has now become the priority of governments and world organizations. Our approach proposes a new kind of finality: as saving and maintaining physical object cost a lot for museums, and sometimes dismantling is impossible as the machine falls in ruin, we propose to preserve it as a numerical object. The aim of this research is to define the global process and technologies used for imple-menting a numerical model of old machines. The final aim is to constitute a new reference for museologic actors, using actual techniques and methods for putting old machines and technical means in “virtual use”, taking into account the working situation including human being at work. This process is illustrated by an example we performed: a steam engine

An open-source multi-FPGA modular system for fair benchmarking of true random number generators

International audienceTrue Random Number Generators (TRNG) are cryptographic primitives that exploit intrinsic noise sources in electronic devices. Their quality is linked to the underlying technology, activity of the neighboring circuitry and device environment (temperature, power supply, electromagnetic emanations). Consequently, when comparing TRNGs, they should be tested in identical technology, system architecture and operating conditions. We present a unified hardware platform and related open source tools aimed at fair benchmarking of TRNGs implemented in different FPGA technologies. The platform is accessible remotely. Designers can download related tools from the web site and they can upload their configuration bitstream to the remote FPGA and download random data generated in the same hardware and in the same conditions as other concurrent designs and state-of-the-art generators. The proposed tools were approved in many applications and they guarantee safe acquisition of random sequences at data rates of up to 400 Mbits/s

Une vision produit-process et sa méthodologie dédiée à la sauvegarde du patrimoine technique et industriel sous une forme virtuelle

International audienceLors de la conférence CPI en 2005, nous avons présenté un nouveau champ de recherche émergent : la sauvegarde sous forme virtuelle du patrimoine industriel et technique. Nous avons alors établi l'état de l'art et les hypothèses de premier niveau. Après 2 ans d'investigations, cette communication statue sur l'avancement de nos travaux : mise en place d'une démarche formalisée pour conserver ce patrimoine grâce à un Système d'Information dédié orienté selon une vision Produit-Processus

Virtualization of ancient technical objects: a new design process and its inter-disciplinary team

International audienceContemporary engineering processes require numerous competences and knowledge using different semantics. Our research consists to design virtually ancient technical objects. The approach we have developed is a new kind of design process: it is a heritage reverse-engineering methodology. It requires a project team with many jobs which, until then, have never collaborate together or not yet: it is an inter disciplinary team. An example will demonstrate our proposal for making old technical objects alive again and how human sciences and technical sciences can merge together. The case study is a steam boat designed in 1861 by DCNS Propulsion

Advanced Industrial Archaeology: A new reverse-engineering process for contextualizing and digitizing ancient technical objects

International audienceSince virtual engineering has been introduced inside industries, time processes have been reduced and products are more adapted to customer needs. Nowadays, the DMU is the centre point for all teams: design, manufacturing, communication etc. However, physical mock-ups and prototypes are sometimes requested. Consequently, a back-and-forth action between the real and the virtual worlds is necessary. Our research team has developed a reverse-engineering methodology for capturing technical characteristics of industrial objects but also for capitalizing knowledge and know-how which are required for contextualizing life cycles. More precisely, we work with ancient industrial machines. It is what we call Advanced Industrial Archaeology. Thanks to the coupling of different kinds of 3D digitalization technologies and CAD software, we are able to re-design old industrial objects and old processes. To illustrate our proposal, we will describe one of the experiments we have done with a salt-washing machine which is nearly 100 years old: from the global 3D digitalization of the plant to precise parts design, we have rediscovered the enterprise process and understand its integration in the economic context

Virtualization of ancient technical objects: a new design process and its inter-disciplinary team

International audienceContemporary engineering processes require numerous competences and knowledge using different semantics. Our research consists to design virtually ancient technical objects. The approach we have developed is a new kind of design process: it is a heritage reverse-engineering methodology. It requires a project team with many jobs which, until then, have never collaborate together or not yet: it is an inter disciplinary team. An example will demonstrate our proposal for making old technical objects alive again and how human sciences and technical sciences can merge together. The case study is a steam boat designed in 1861 by DCNS Propulsion

A case study of capitalisation and valorisation of our technical heritage

International audienceFor the 2008 CIRP Design conference, we have presented a scientific article dealing with a new way of thinking our technical heritage: we would like to preserve it as a digital object. Project deals with a physical mock-up of Nantes city built in 1899 and used for the Universal exposition in France in 1900 in Paris. The heritage object is nowadays in the museum but exposed as a fish inside an aquarium. Thanks to a virtual system coupling a tactile screen with semantic research modules, 3D active screen and light pointer, it will allow the visitor to better understand the mock-up and emphasize important places of Nantes city life. However it does not mean beautiful 3D animation with nice static rendering; indeed, we create virtual mockups which are dynamically operating. We use CAD software and engineering simulation tools. Nowadays the global methodology has been improved: it is named Advanced Industrial Archaeology. In this communication, we will detail a new experimentation done in partnership with a French museum: the Château des Ducs de Bretagne in France. This project deals with a physical mock-up of Nantes city built in 1899 and exposed in 1900 for the World Fair that took place in Paris, France. The heritage object is nowadays in the museum but exposed as “a fish inside an aquarium”. Thanks to a virtual system coupling a tactile screen with semantic research modules, a 3D active screen and a light pointer, it will allow the visitor to better understand the mock-up and emphasize important places of the city. The mock-up represents our industrial heritage with old shipyards of Nantes