2,709 research outputs found
Feshbach resonances in ultracold ^{6,7}Li + ^{23}Na atomic mixtures
We report a theoretical study of Feshbach resonances in Li + Na
and Li + Na mixtures at ultracold temperatures using new accurate
interaction potentials in a full quantum coupled-channel calculation. Feshbach
resonances for in the initial collisional open channel LiNa are found to agree with previous
measurements, leading to precise values of the singlet and triplet scattering
lengths for the LiNa 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
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