Spontaneous dissociation of long-range Feshbach molecules

TL;DR

This paper presents a universal formula for the lifetime of Feshbach molecules in cold gases, showing decay suppression at large scattering lengths, validated by experiments with rubidium dimers.

Contribution

It introduces a universal theoretical model for molecule lifetime based on scattering length and loss rates, supported by exact calculations and experimental data.

Findings

Decay suppression over several orders of magnitude at large scattering lengths

Universal formula accurately predicts molecule lifetimes

Good agreement with recent rubidium dimer experiments

Abstract

We study the spontaneous dissociation of diatomic molecules produced in cold atomic gases via magnetically tunable Feshbach resonances. We provide a universal formula for the lifetime of these molecules that relates their decay to the scattering length and the loss rate constant for inelastic spin relaxation. Our universal treatment as well as our exact coupled channels calculations for $^{85}$Rb dimers predict a suppression of the decay over several orders of magnitude when the scattering length is increased. Our predictions are in good agreement with recent measurements of the lifetime of $^{85}$Rb$_2$.