Feshbach resonances in ultracold ^{6,7}Li + ^{23}Na atomic mixtures

We report a theoretical study of Feshbach resonances in $^{6}$Li + $^{23}$Na and $^{7}$Li + $^{23}$Na mixtures at ultracold temperatures using new accurate interaction potentials in a full quantum coupled-channel calculation. Feshbach resonances for $l=0$ in the initial collisional open channel $^6$Li$(f=1/2, m_f=1/2) + ^{23}$Na$(f=1, m_f=1)$ are found to agree with previous measurements, leading to precise values of the singlet and triplet scattering lengths for the $^{6,7}$Li$+^{23}$Na pairs. We also predict additional Feshbach resonances within experimentally attainable magnetic fields for other collision channels.Comment: 4 pages, 3 figure

Controllable binding of polar molecules and meta-stability of 1-D gases with attractive dipole forces

We explore one-dimensional (1-D) samples of ultracold polar molecules with attractive dipole-dipole interactions and show the existence of a repulsive barrier due to a strong quadrupole interaction between molecules. This barrier can stabilize a gas of ultracold KRb molecules and even lead to long-range wells supporting bound states between molecules. The properties of these wells can be controlled by external electric fields, allowing the formation of long polymer-like chains of KRb, and studies of quantum phase transitions by varying the effective interaction between molecules. We discuss the generalization of those results to other systems

Isolement, identification et caractérisation de souches québécoises du nématode Caenorhabditis elegans

Quatre-vingt-treize souches du nématode libre du sol #Caenorhabditis elegans ont été isolées à partir d'échantillons de sol et de matières organiques en décomposition provenant de différents sites du Québec. L'examen morphologique et des croisements avec la souche anglaise "standard" Bristol (N2) ont servi à l'identification des souches. Quelques caractéristiques biologiques (durée du développement oeuf-adulte, viabilité, longueur, fécondité à quatre différentes températures) de six souches de #C. elegans isolées de quatre régions du Québec ont été étudiées. Une étude préliminaire de la sensibilité de ces souches à quatre substances toxiques (la diphénylamine, le pentachlorophénol, le 4-chlorobiphényle et le 2,2'-dichlorobiphényle) a démontré l'existence de différences entre ces souches. (Résumé d'auteur

Rubidium Rydberg macrodimers

We explore long-range interactions between two atoms excited into high principal quantum number n Rydberg states, and present calculated potential energy surfaces (PES) for various symmetries of doubly excited ns and np rubidium atoms. We show that the PES for these symmetries exhibit deep (~GHz) potential wells, which can support very extended (~micrometers) bound vibrational states (macrodimers). We present n-scaling relations for both the depth De of the wells and the equilibrium separations Re of these macrodimers, and explore their response to small electric fields and stability with respect to predissociation. Finally, we present a scheme to form and study these macrodimers via photoassociation, and show how one can probe the various \ell-character of the potential wells