Avalanche Mechanism for the Enhanced Loss of Ultracold Atoms

Abstract

In several experiments with ultracold trapped atoms, a narrow loss feature has been observed near an {\it atom-dimer resonance}, at which there is an Efimov trimer at the atom-dimer threshold. The conventional interpretation of these loss features is that they are produced by the {\it avalanche mechanism}, in which the energetic atom and dimer from 3-body recombination undergo secondary elastic collisions that produce additional atoms with sufficient energy to escape from the trapping potential. We use Monte Carlo methods to calculate the average number of atoms lost and the average heat generated by recombination events in a Bose-Einstein condensate and in a thermal gas. We improve on previous models by taking into account the energy-dependence of the cross sections, the spacial structure of the atom cloud, and the elastic scattering of the atoms. We show that the avalanche mechanism cannot produce a narrow loss feature near the atom-dimer resonance. The number of atoms lost from a recombination event can be more than twice as large as the 3 that would be obtained in the absence of secondary collisions. However the resulting loss feature is broad and its peak is at a scattering length that is larger than the atom-dimer resonance and depends on the trap depth.

27 pages, 9 figures

References in corpus (9)

• Observation of an Efimov spectrum in an atomic system
• Three-body recombination at large scattering lengths in an ultracold atomic gas
• Observation of an Efimov-like resonance in ultracold atom-dimer scattering
• Evidence for Universal Four-Body States Tied to an Efimov Trimer
• Universal Properties of the Four-Body System with Large Scattering Length
• Study of Efimov physics in two nuclear-spin sublevels of 7Li
• Three-Body Recombination of Identical Bosons with a Large Positive Scattering Length at Nonzero Temperature
• The Avalanche Mechanism for Atom Loss near an Atom-Dimer Efimov Resonance
• Four-body legacy of the Efimov effect

Cited by in corpus (6)

• Finite range corrections near a Feshbach resonance and their role in the Efimov effect
• Observation of Efimov Universality across a Non-Universal Feshbach Resonance in \textsuperscript{39}K
• Looking for "avalanche-mechanism" loss at an atom-molecule Efimov resonance
• Observation of Anomalous Decay of a Polarized Three-Component Fermi Gas
• Atom Loss Resonances in a Bose-Einstein Condensate
• Three-body Physics in the Impurity Limit of 39K Bose-Einstein Condensates