Exploring the van der Waals Atom-Surface attraction in the nanometric range

The van der Waals atom-surface attraction, scaling as C3 z-3 for z the atom-surface distance, is expected to be valid in the distance range 1-1000 nm, covering 8-10 orders of magnitudes in the interaction energy. A Cs vapour nanocell allows us to analyze the spectroscopic modifications induced by the atom-surface attraction on the 6P3/2->6D5/2 transition. The measured C3 value is found to be independent of the thickness in the explored range 40-130 nm, and is in agreement with an elementary theoretical prediction. We also discuss the specific interest of exploring short distances and large interaction energy.Comment: to appear in Europhysics Letter

Progress in atom chips and the integration of optical microcavities

We review recent progress at the Centre for Cold Matter in developing atom chips. An important advantage of miniaturizing atom traps on a chip is the possibility of obtaining very tight trapping structures with the capability of manipulating atoms on the micron length scale. We recall some of the pros and cons of bringing atoms close to the chip surface, as is required in order to make small static structures, and we discuss the relative merits of metallic, dielectric and superconducting chip surfaces. We point out that the addition of integrated optical devices on the chip can enhance its capability through single atom detection and controlled photon production. Finally, we review the status of integrated microcavities that have recently been demonstrated at our Centre and discuss their prospects for future development.Comment: 12 pages, 6 figures, proceedings of the ICOLS07 conferenc

The Ergonomist: A Full Design Actor Example of an Ergonomic Action

AbstractActivity-centered ergonomics has developed an approach to provide support for design projects which comprises ergonomics work analysis, participatory design and simulation of work. This approach leads us to appreciate the reality of work in order to design systems which are adapted to human's abilities and also to the tasks to be performed. However, beyond the technical recommendations, ergonomists may take part in project management. In fact, for some years now, they are no longer satisfied with merely providing the information and advice they have discovered through work analysis. In order to take into account functional requirements of work situations, they now try to influence the very way in which projects are managed and thus influence the design process itself. This perspective sheds a new light on the ergonomist's positioning as a full design actor or as a co-designer. This type of contribution is possible from the early phases of feasibility until the installation start-up. We will try to illustrate this perspective through the results of an ergonomic intervention in an industrial design project

Negative-index media for matter-wave optics

We consider the extension of optical meta-materials to matter waves. We show that the generic property of pulsed comoving magnetic fields allows us to fashion the wave-number dependence of the atomic phase shift. It can be used to produce a transient negative group velocity of an atomic wave packet, which results into a negative refraction of the matter wave. Application to slow metastable argon atoms Ar*(3P2) shows that the device is able to operate either as an efficient beam splitter or an atomic meta-lens. Implications of "meta-media" in atom optics are considered.Comment: 4 pages, 4 figures, submitted at PRL 4 November 200

Anisotropic Atom-Surface Interactions in the Casimir-Polder Regime

The distance-dependence of the anisotropic atom-wall interaction is studied. The central result is the 1/z^6 quadrupolar anisotropy decay in the retarded Casimir-Polder regime. Analysis of the transition region between non-retarded van der Waals regime (in 1/z^3) and Casimir-Polder regime shows that the anisotropy cross-over occurs at very short distances from the surface, on the order of 0.03 Lambda, where Lambda is the atom characteristic wavelength. Possible experimental verifications of this distance dependence are discussed.Comment: 5 pages, 2 figure

Atom detection and photon production in a scalable, open, optical microcavity

A microfabricated Fabry-Perot optical resonator has been used for atom detection and photon production with less than 1 atom on average in the cavity mode. Our cavity design combines the intrinsic scalability of microfabrication processes with direct coupling of the cavity field to single-mode optical waveguides or fibers. The presence of the atom is seen through changes in both the intensity and the noise characteristics of probe light reflected from the cavity input mirror. An excitation laser passing transversely through the cavity triggers photon emission into the cavity mode and hence into the single-mode fiber. These are first steps towards building an optical microcavity network on an atom chip for applications in quantum information processing.Comment: 4 pages, 4 figures. A typographical error in the published paper has been corrected (equation of the corrected normalized variance, page 3, 2nd paragraph

Les logiques d’examen au Conseil des bâtiments civils

Le Conseil des Bâtiments civils fut une institution entièrement dédiée à l’examen de l’architecture. Au fil de ses séances, ses membres formulaient des avis, à l’intention du ministre de l’Intérieur, sur tous les projets d’architecture publique projetés en France. À travers l’examen des projets architecturaux qui lui étaient soumis, le Conseil des Bâtiments civils exerçait, sinon une censure sur l’architecture publique, au moins une influence notable sur la nature architecturale des projets d’édifices qu’il révisait. La grande série continue des procès-verbaux des séances du Conseil des bâtiments civils de 1795 à 1848, conservée dans la sous-série F21 des Archives nationales de France, offre ainsi au chercheur une source sans équivalent non seulement pour l’étude de l’architecture publique mais aussi pour l’étude du jugement architectural. Cet article propose de s’intéresser au cœur même de la délibération du Conseil des bâtiments civils. Après avoir examiné la question des prérogatives du Conseil, il présente la procédure mise en œuvre par le Conseil pour l’examen des affaires afin de présenter quelques pistes méthodologiques pour aborder ce gigantesque matériau textuel dont l’étude permet d’envisager, à nouveaux frais, la question de l’éclectisme en architecture.The Conseil des bâtiments civils was an institution entirely dedicated to the examination of architecture. During its meetings, its members formulated opinions, for the Minister of the Interior, on all public architecture projects planned in France. Through the examination of the architectural projects submitted to it, the Council of Civil Buildings exercised, if not a censorship on public architecture, at least a notable influence on the architectural nature of the building projects that it revised. The procès-verbaux of the meetings of the Council of Civil Buildings from 1795 to 1848, preserved in the F21 sub-series of the National Archives of France, thus offers the researcher an unparalleled source not only for the study of the public architecture but also for the study of architectural judgment. This article proposes to examine the very heart of the deliberations of the Civil Building Council. After having examined the question of the prerogatives of the Council, it presents the procedure implemented by the Council for the examination of the cases in order to present some methodological ways to approach this gigantic textual material whose study makes it possible to envisage, with new expenses, the question of eclecticism in architecture.Der Conseil des bâtiments civils war eine ganz der Architekturprüfung gewidmete Institution. In den Sitzungen des Conseil formulierten seine Mitglieder Stellungnahmen für das Innenministerium über alle öffentlichen Bauvorhaben in Frankreich. Mit seiner Expertise zu den ihm vorgelegten architektonischen Projekten übte der Conseil des bâtiments civils eine wenn nicht als Zensur zu bezeichnende, so doch als entscheidendes Votum zu wertende Einflussnahme auf die architektonische Ausgestaltung des öffentlichen Bauens aus. Die vollständig in den Archives nationales de France unter der Signatur F21 bewahrten Bestände des Conseil des bâtiments civils von 1795 bis 1848 bieten der Forschung eine unvergleichliche Quelle nicht nur zum öffentlichen Bauen, sondern darüber hinaus zu architektonischen Gutachten. Dieser Beitrag möchte sich insbesondere mit den eigentlichen Verhandlungen des Conseil des bâtiments civils beschäftigen. Zunächst werden dabei die Vorrechte des Conseils betrachtet, anschließend wird das vom Conseil vollzogene Prüfungsverfahren erläutert, um darauf aufbauend methodische Ansätze zum Umgang mit dem umfangreichenden Textmaterial vorzustellen, die zu einer eingehenderen Untersuchung des architektonischen Eklektizismus beitragen können

Dicke Coherent Narrowing in Two-Photon and Raman Spectroscopy of Thin Vapour Cells

The principle of coherent Dicke narrowing in a thin vapour cell, in which sub-Doppler spectral lineshapes are observed under a normal irradiation for a l/2 thickness, is generalized to two-photon spectroscopy. Only the sum of the two wave vectors must be normal to the cell, making the two-photon scheme highly versatile. A comparison is provided between the Dicke narrowing with copropagating fields, and the residual Doppler-broadening occurring with counterpropagating geometries. The experimental feasibility is discussed on the basis of a first observation of a two-photon resonance in a 300 nm-thick Cs cell. Extension to the Raman situation is finally considered

Quadrupole transitions near interface: general theory and application to atom inside a planar cavity

Quadrupole radiation of an atom in an arbitrary environment is investigated within classical as well as quantum electrodynamical approaches. Analytical expressions for decay rates are obtained in terms of Green function of Maxwell equations. The equivalence of both approaches is shown. General expressions are applied to analyze the quadrupole decay rate of an atom placed between two half spaces with arbitrary dielectric constant. It is shown that in the case when the atom is close to the surface, the total decay rate is inversely proportional to the fifth power of distance between an atom and a plane interface.Comment: 18 pages, 7 figure