Atom-dimer p-wave resonance for fermionic mixtures with different masses

TL;DR

This paper demonstrates a strong p-wave atom-dimer resonance in $^6$Li-$^{40}$K mixtures near a Feshbach resonance, influenced by the mass ratio, with implications for the physical properties of fermionic mixtures.

Contribution

It reveals the presence of a p-wave resonance due to a virtual bound state in atom-dimer scattering and explores its dependence on mass ratio, offering new insights into fermionic mixture behavior.

Findings

Identification of a p-wave resonance at low energy near Feshbach resonance.

Resonance linked to a virtual bound state transitioning to a real bound state at mass ratio 8.17.

Potential impact on the equation of state and collective modes of fermionic mixtures.

Abstract

We show that, near a Feshbach resonance, a strong p-wave resonance is present at low energy in atom-dimer scattering for $^6$Li-$^{40}$K fermionic mixtures. This resonance is due to a virtual bound state, in the atom-dimer system, which is present at this low energy. When the mass ratio between the two fermionic elements is increased, this virtual bound state goes to a known real bound state which appears when the mass ratio reaches 8.17. This resonance should affect a number of physical properties. These include the equation of state of unbalanced mixtures at very low temperature but also the equation of state of balanced mixtures at moderate or high temperature. The frequency and the damping of collective modes should also provide a convenient way to evidence this resonance. Finally it should be possible to modify the effective mass of one the fermionic species by making use of an optical lattice. This would allow to study the strong dependence of the resonance as a function of the mass ratio of the two fermionic elements.