122 research outputs found
Universal rate constants for reactive collisions of ultracold molecules
A simple quantum defect model gives analytic expressions for the complex
scattering length and threshold collision rates of ultracold molecules. If the
probability of reaction in the short-range part of the collision is high, the
model gives universal rate constants for s- and p-wave collisions that are
independent of short-range dynamics. This model explains the magnitudes of the
recently measured rate constants for collisions of two ultracold 40K87Rb
molecules, or an ultracold 40K atom with the 40K87Rb molecule [Ospelkaus et
al., Science 327, 853 (2010)].Comment: 4 pages, 2 figures; v2: final version, accepted for publication in
Physical Review Letter
Simple Theoretical Models for Resonant Cold Atom Interactions
Magnetically tunable scattering resonances have been used with great success
for precise control of s-wave scattering lengths in ultracold atomic
collisions. We describe relatively simple yet quite powerful analytic
treatments of such resonances based on the analytic properties of the van der
Waals long range potential. This theory can be used to characterize a number of
properties of specific resonances that have been used successfully in various
experiments with Rb, Rb, K, and Li. Optical Feshbach
resonances are also possible and may be practical with narrow intercombination
line photoassociative transitions in species like Sr and Yb.Comment: To be published in the Proceedings of the 20th International
Conference on Atomic Physics, held in Innsbruck, Austria, July 200
Optical Feshbach resonances of Alkaline-Earth atoms in a 1D or 2D optical lattice
Motivated by a recent experiment by Zelevinsky et al. [Phys. Rev. Lett. 96,
203201], we present the theory for photoassociation and optical Feshbach
resonances of atoms confined in a tight one-dimensional (1D) or two-dimensional
(2D) optical lattice. In the case of an alkaline-earth intercombination
resonance, the narrow natural width of the line makes it possible to observe
clear manifestations of the dimensionality, as well as some sensitivity to the
scattering length of the atoms. Among possible applications, a 2D lattice may
be used to increase the spectroscopic resolution by about one order of
magnitude. Furthermore, a 1D lattice induces a shift which provides a new way
of determining the strength of a resonance by spectroscopic measurements.Comment: 12 pages, 4 figures. Typos were corrected and a connection was made
to the fermionization of boson
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