Polaronic atom-trimer continuity in three-component Fermi gases

TL;DR

This paper investigates the crossover physics in three-component Fermi gases, revealing a smooth transition from atom-like to trimer-like impurity states and identifying a sharp transition to dimer states, with implications for ultracold atom experiments.

Contribution

It introduces a variational approach near a narrow Feshbach resonance to describe polaronic atom-trimer continuity in three-component Fermi gases, a novel theoretical insight.

Findings

Impurity smoothly transitions from atom to trimer with increasing attraction.

A sharp transition from trimer to dimer state is identified.

The polaronic wave function captures the atom-trimer continuity.

Abstract

Recently it has been proposed that three-component Fermi gases may exhibit a new type of crossover physics in which an unpaired Fermi sea of atoms smoothly evolves into that of trimers in addition to the ordinary BCS-BEC crossover of condensed pairs. Here we study its corresponding polaron problem in which a single impurity atom of one component interacts with condensed pairs of the other two components with equal populations. By developing a variational approach in the vicinity of a narrow Feshbach resonance, we show that the impurity atom smoothly changes its character from atom to trimer with increasing the attraction and eventually there is a sharp transition to dimer. The emergent polaronic atom-trimer continuity can be probed in ultracold atoms experiments by measuring the impurity spectral function. Our novel crossover wave function properly incorporating the polaronic atom-trimer continuity will provide a useful basis to further investigate the phase diagram of three-component Fermi gases in more general situations.