Collisional properties of weakly bound heteronuclear dimers

TL;DR

This paper develops a theoretical framework to analyze collisional properties of weakly bound heteronuclear dimers, revealing conditions under which inelastic rates are suppressed, aiding the understanding of their stability and three-body interactions.

Contribution

A new theoretical approach to describe four-atom heteronuclear dimer collisions, enabling precise calculation of elastic and inelastic rates and linking inelastic measurements to three-body parameters.

Findings

Inelastic rates can be lower than elastic collision rates.

Inelastic rate measurements can determine three-body parameters.

The approach applies regardless of heavy atom quantum statistics.

Abstract

We consider collisional properties of weakly bound heteronuclear molecules (dimers) formed in a two-species mixture of atoms with a large mass difference. We focus on dimers containing light fermionic atoms as they manifest collisional stability due to an effective dimer-dimer repulsion originating from the exchange of the light atoms. In order to solve the dimer-dimer scattering problem we develop a theoretical approach, which provides a physically transparent and quantitative description of this four-atom system in terms of three- and two-body observables. We calculate the elastic scattering amplitude and the rates of inelastic processes such as the trimer formation and the relaxation of dimers into deeply bound molecular states. Irrespective of whether the heavy atoms are bosons or fermions, the inelastic rate can be significantly lower than the rate of elastic collisions. Moreover, the measurement of the inelastic rate which is a four-body observable, can be an efficient and precise tool for determining three-body observables such as the three-body parameter, positions of Efimov states and their lifetimes.