The Avalanche Mechanism for Atom Loss near an Atom-Dimer Efimov Resonance

TL;DR

This paper investigates how Efimov trimers near the atom-dimer threshold enhance atom loss in ultracold gases via an avalanche mechanism, affecting Efimov parameter measurements.

Contribution

It introduces a Monte Carlo simulation that accounts for energy-dependent cross sections and spatial structure to analyze atom loss and heating near Efimov resonances.

Findings

Atom loss can exceed three atoms per recombination event near Efimov states.

The avalanche mechanism significantly influences atom loss rates without producing narrow loss features.

Results impact the interpretation of Efimov resonance measurements.

Abstract

An Efimov trimer near the atom-dimer threshold can increase the atom loss rate in ultracold trapped atoms through the {\it avalanche mechanism} proposed by Zaccanti et al. A 3-body recombination event creates an energetic atom and dimer, whose subsequent elastic collisions 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 both a Bose-Einstein condensate and a thermal gas. We take into account the energy-dependence of the cross sections and the spatial structure of the atom cloud. We confirm that the number of atoms lost can be much larger than the naive value 3 if there is an Efimov trimer near the atom-dimer threshold. This does not produce a narrow loss feature, but it can significantly affect the determination of Efimov parameters.