A study of the dimer-trimer crossover in a driven three-component Fermi gas

TL;DR

This paper develops an Effective Field Theory to analyze the dimer-trimer crossover in a driven three-component Fermi gas, predicting controllable energy branch crossings in medium.

Contribution

It introduces a novel EFT framework for a driven three-species Fermi system and analytically predicts dimer-trimer energy crossings in medium.

Findings

Derived analytical expressions for binding energies in vacuum and medium.

Predicted a controllable crossing between dimer and trimer energy branches.

Discussed implications for experimental control of few-body states.

Abstract

We develop an Effective Field Theory (EFT) for a system with three distinguishable atomic species and present a variational calculation of the two and three-body binding energies in vacuum and in the presence of a single Fermi sea. Specifically, we consider the case where the interaction between first two atomic species is externally driven so as to produce a (non-universal) closed-channel dimer whose coupling can be controlled independently of all other interactions. We then model the remaining interactions as a contact interaction between the dimer and a third atomic species which forms the medium. We derive analytical expressions for the dimer and trimer binding energies in vacuum and in medium, and in the latter case we predict a crossing between the dimer and trimer branches as a function of the atom-dimer scattering length, analogous to the usual polaron and molecule problem. Furthermore, we show that the position of this crossing can be controlled by varying the atom-atom coupling that results from the external drive and we discuss the implications of these findings.