Universal Trimers induced by Spin-Orbit Coupling in Ultracold Fermi Gases

TL;DR

This paper demonstrates that synthetic spin-orbit coupling can induce universal three-body bound states in ultracold Fermi gases, enabling control over atom-dimer resonances and expanding the understanding of few-body physics.

Contribution

It reveals that spin-orbit coupling induces universal trimers at smaller mass ratios, a phenomenon absent without SO coupling, and shows how to control these states via SO strength.

Findings

SO coupling induces universal trimers at smaller mass ratios.

Trimer energies are independent of high-energy cutoff, confirming universality.

Atom-dimer resonance can be tuned by adjusting SO coupling strength.

Abstract

In this letter we address the issue how synthetic spin-orbit (SO) coupling can strongly affect three-body physics in ultracold atomic gases. We consider a system which consists of three fermionic atoms, including two spinless heavy atoms and one spin-1/2 light atom subjected to an isotropic SO coupling. We find that SO coupling can induce universal three-body bound states with negative s-wave scattering length at a smaller mass ratio, where no trimer bound state can exist if in the absence of SO coupling. The energies of these trimers are independent of high-energy cutoff, and therefore they are universal ones. Moreover, the resulting atom-dimer resonance can be effectively controlled by SO coupling strength. Our results can be applied to systems like ${}^6$Li and ${}^{40}$K mixture.