Bose-Einstein condensates in fast rotation

In this short review we present our recent results concerning the rotation of atomic Bose-Einstein condensates confined in quadratic or quartic potentials, and give an overview of the field. We first describe the procedure used to set an atomic gas in rotation and briefly discuss the physics of condensates containing a single vortex line. We then address the regime of fast rotation in harmonic traps, where the rotation frequency is close to the trapping frequency. In this limit the Landau Level formalism is well suited to describe the system. The problem of the condensation temperature of a fast rotating gas is discussed, as well as the equilibrium shape of the cloud and the structure of the vortex lattice. Finally we review results obtained with a quadratic + quartic potential, which allows to study a regime where the rotation frequency is equal to or larger than the harmonic trapping frequency.Comment: Laser Physics Letters 2, 275 (2005

Interference of an array of independent Bose-Einstein condensates

We have observed high-contrast matter wave interference between 30 Bose-Einstein condensates with uncorrelated phases. Interference patterns were observed after independent condensates were released from a one-dimensional optical lattice and allowed to expand and overlap. This initially surprising phenomenon is explained with a simple theoretical model which generalizes the analysis of the interference of two independent condensates

Design and synthesis of triphenylphosphonium-porphyrin@xylan nanoparticles for anticancer photodynamic therapy

Most photosensitizers (PS) suffer from a lack of water solubility and from a low selectivity toward tumor cells. Delivery systems using nanoparticles make it possible to improve PS water solubility, and also tumor targeting via the enhanced permeability and retention (EPR) effect. Among the organelles, mitochondria are attractive target sites for drug-delivery strategies since they perform a variety of key cellular processes. Our study was aimed at synthesizing nanoparticles consisting of xylan-carrying porphyrins attached to a triphenylphosphonium moiety, in order to enhance the PDT effect through mitochondrial targeting. Hybrid nanoparticles were designed that consisted of a silica core coated with xylan substituted with porphyrin derivatives carrying a triphenylphosphonium moiety. These hybrid nanoparticles have been constructed, along with their counterparts devoid of silica core, taking into consideration the controversy surrounding the use of silica nanoparticles. Phototoxicity experiments, conducted against the HCT-116 and HT-29 colorectal cancer cell lines, showed that nanoparticles with porphyrins bearing a triphenylphosphonium moiety exhibited an enhanced photocytotoxic effect in comparison with free porphyrin or nanoparticles with porphyrins without the triphenylphosphonium moiety

Design and synthesis of triphenylphosphonium-porphyrin@xylan nanoparticles for anticancer photodynamic therapy

Most photosensitizers (PS) suffer from a lack of water solubility and from a low selectivity toward tumor cells. Delivery systems using nanoparticles make it possible to improve PS water solubility, and also tumor targeting via the enhanced permeability and retention (EPR) effect. Among the organelles, mitochondria are attractive target sites for drug-delivery strategies since they perform a variety of key cellular processes. Our study was aimed at synthesizing nanoparticles consisting of xylan-carrying porphyrins attached to a triphenylphosphonium moiety, in order to enhance the PDT effect through mitochondrial targeting. Hybrid nanoparticles were designed that consisted of a silica core coated with xylan substituted with porphyrin derivatives carrying a triphenylphosphonium moiety. These hybrid nanoparticles have been constructed, along with their counterparts devoid of silica core, taking into consideration the controversy surrounding the use of silica nanoparticles. Phototoxicity experiments, conducted against the HCT-116 and HT-29 colorectal cancer cell lines, showed that nanoparticles with porphyrins bearing a triphenylphosphonium moiety exhibited an enhanced photocytotoxic effect in comparison with free porphyrin or nanoparticles with porphyrins without the triphenylphosphonium moiety

Rotations d'un condensat de Bose-Einstein

This thesismanuscript presents experimental results on rotating Bose-Einsteincondensates. Due to the condensate's coherence, rotation generallyinvolves phase singularities called vortices. The isolation andobservation of a single vortex line have enabled the study of itsdynamics in an elongated condensate. The equilibrium shape of thevortex line as well as its evolution on long time scales werecharacterized. The vibrations of the line were shown to influencethe damping of surface modes. The fast rotation limit was alsostudied. For intermediate rotation speeds, it is characterized bya large number of vortices arranged in a so-called Abrikosovlattice. For higher rotation speeds, different phases are expecteddepending on the shape of the trapping potential. This limit wasstudied in the case of an hybrid potential containing a smallquartic term. We have identified the rotating clouds by variousmethods, revealing original properties. The observation of suchclouds is the first step to a possible future observation ofstrongly correlated states close to the fractional quantum Hallregime.Ce mémoire de thèse présente les résultats d'un séried'expériences sur des condensats de Bose-Einstein en rotation. Dufait de la cohérence d'un condensat, la rotation s'introduitgénéralement sous la forme de singularités de phase appeléesvortex. L'isolation et l'observation d'une unique ligne de vortexont permis d'étudier sa dynamique dans un condensat allongé. Laforme d'équilibre de la ligne de vortex ainsi que son évolutionsur des échelles de temps longues ont été caractérisées. Par leureffet sur l'amortissement des modes de surface, les modes devibration de la ligne ont été mis en évidence. La limite desrotations rapides a également été étudiée. Pour des vitesses derotation intermédiaires, elle est caractérisée par un grand nombrede vortex arrangés en réseaux d'Abrikosov. Pour des vitessesencore plus grandes, différentes phases sont attendues selon laforme du potentiel. Cette limite a été étudiée dans le cas d'unpotentiel hybride contenant un petit terme quartique. Les nuagesen rotation, que nous avons caractérisés par plusieurs méthodes,se révèlent avoir un comportement original. Leur observationconstitue un premier pas vers celle de phases corrélées proches durégime Hall quantique fractionnaire

Rotations d'un condensat de Bose-Einstein

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Echelle d'hétéro evaluation de la douleur aigüe utilisant un coefficient douloureux (validation multicentrique dans les services d'urgences)

INTRODUCTION : Dans les services d'accueil des urgences (SAU) où la douleur est fréquente, seule des échelles d'auto évaluation ont été validées. Notre étude avait pour objectif de valider une nouvelle échelle d'hétéro évaluation aux urgences (échelle HECD). METHODES : L'échelle HECD est basée sur 4 éléments de l'inspection au repos auxquels a été rajouté l'item coefficient douloureux selon le motif d'entrée au SAU. Ce nouvel outil a été comparé chez l'adulte à l'échelle numérique (EN) par le biais d'une étude prospective multicentrique dans 2 SAU de la région Midi-Pyrénées. RESULTATS : 168 patients ont été inclus, d'un âge moyen de 44 ans (+-22), avec un sex ratio H/F de 1 ,89. Le coefficient de corrélation de Spearman avec l'EN était important ( = 0.71, p<0.0001), la reproductibilité interindividuelle très bonne ( = 0.85, p<0.0001). CONCLUSION : L'échelle HECD est utilisable en urgence et ses résultats sont bien corrélés à ceux de l'EN.TOULOUSE3-BU Santé-Centrale (315552105) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Fast rotation of a Bose-Einstein condensate

https://pro.college-de-france.fr/jean.dalibard/publications/bretin04.pdfInternational audienceWe study the rotation of a 87Rb Bose-Einstein condensate confined in a quadratic plus quartic potential. This trap configuration allows one to increase the rotation frequency of the gas above the trap frequency. In such a fast rotation regime we observe a dramatic change in the appearance of the quantum gas. The vortices which were easily detectable for a slower rotation become much less visible, and their surface density is well below the value expected for this rotation frequency domain. We discuss some possible tracks to account for this effect

Coherent Interferometry Algorithms for Photoacoustic Imaging

The aim of this paper is to develop new coherent interferometry (CINT) algorithms to correct the effect of an unknown cluttered sound speed (random fluctuations around a known constant) on photoacoustic images. By back-propagating the correlations between the preprocessed pressure measurements, we show that we are able to provide statistically stable photoacoustic images. The preprocessing is exactly in the same way as when we use the circular or the line Radon inversion to obtain photoacoustic images. Moreover, we provide a detailed stability and resolution analysis of the new CINT--Radon algorithms. We also present numerical results to illustrate their performance and to compare them with Kirchhoff--Radon migration functions.European Research Council (MULTIMOD–267184