Evidence for Ground- and Excited-State Efimov Trimers in a Three-State Fermi Gas

TL;DR

This paper reports the observation of Efimov trimer states in a three-state ultracold Fermi gas, linking experimental recombination rates with theoretical predictions and demonstrating a quantum degenerate three-state Fermi system.

Contribution

It provides experimental evidence for ground and excited Efimov trimers in a three-component Fermi gas and connects these to universal Efimov physics predictions.

Findings

Enhanced three-body recombination near Efimov resonances

Agreement between measured rates and zero-range theoretical calculations

First realization of a quantum degenerate three-state Fermi gas with SU(3) symmetry

Abstract

We observe enhanced three-body recombination in an ultracold three-component $^6$Li Fermi gas with large but unequal scattering lengths attributable to an excited Efimov trimer state near the three-atom scattering threshold. We find excellent agreement between the measured three-body recombination rate and the recombination rate calculated in the zero-range approximation where the only free parameters are the Efimov parameters $\kappa_*$ and $\eta_*$. The value of $\kappa_*$ determined by the location of the Efimov resonance we observe at 895 G also predicts the locations of loss features previously observed near 130 and 500 G \cite{Jochim08,OHara09} suggesting that all three features are associated with universal Efimov trimer states. We also report on the first realization of a quantum degenerate three-state Fermi gas with approximate SU(3) symmetry.