Enhancing the observability of the Efimov effect in ultracold atomic gas mixtures

We discuss the prospects for observing the characteristic features of the Efimov effect in a two-component ultracold atomic gas near an interspecies Feshbach resonance. In the ultracold regime, the Efimov effect is expected to be manifested in the three-body collision rates through the appearance of series of minima or maxima as a function of the two-body $s$-wave scattering length $a$. Here, we propose the observation of this Efimov physics through measurements of the inelastic three-body rate constants near a Feshbach resonance. Our analysis suggests that boson-fermion mixtures, where the bosons are much heavier than the fermions, are the most favorable system to observe such features.

Figure 1

Coefficients $s_0$ and $p_0$ as a function of the mass ratio $\delta$ for (a) three-body recombination and (b) vibrational relaxation for boson-fermion mixtures.

Figure 2

Recombination for model ${}^{133}\mathrm{Cs}+{}^{133}\mathrm{Cs}+{}^6\mathrm{Li}$ collisions into weakly bound $s$-wave ${}^{133}\mathrm{Cs}{}^6\mathrm{Li}$ molecules (solid line with circles) and in to deeply bound $p$-wave ${}^{133}\mathrm{Cs}{}^6\mathrm{Li}$ molecules (dashed line with circles). The solid line represents the analytical expression [Eq. (1)].