Suppression of Unitary Three-body Loss in a Degenerate Bose-Fermi Mixture

TL;DR

This paper investigates how three-body loss in a Bose-Fermi mixture is suppressed at unitarity due to Fermi degeneracy and RKKY interactions, revealing a significant reduction in loss rates.

Contribution

It demonstrates the suppression of three-body loss at unitarity in a Bose-Fermi mixture and introduces a model based on RKKY interactions that quantitatively explains the phenomenon.

Findings

Three-body loss is reduced with increasing Fermi degeneracy.

The RKKY interaction model accurately reproduces experimental data.

Predicted one order of magnitude reduction in loss coefficient in deep Fermi degeneracy.

Abstract

We study three-body loss in an ultracold mixture of a thermal Bose gas and a degenerate Fermi gas. We find that at unitarity, where the interspecies scattering length diverges, the usual inverse-square temperature scaling of the three-body loss found in non-degenerate systems is strongly modified and reduced with the increasing degeneracy of the Fermi gas. While the reduction of loss is qualitatively explained within the few-body scattering framework, a remaining suppression provides evidence for the long-range RKKY interactions mediated by fermions between bosons. Our model based on RKKY interactions quantitatively reproduces the data without free parameters, and predicts one order of magnitude reduction of the three-body loss coefficient in the deeply Fermi-degenerate regime.