Atom-molecule coexistence and collective dynamics near a Feshbach resonance of cold fermions

TL;DR

This paper develops a theoretical model for a degenerate Fermi gas near a Feshbach resonance, describing atom-molecule coexistence, stability, phase diagram, and dynamics, relevant for current experiments.

Contribution

It introduces a Dicke model-based approach to analyze the mixed atom-molecule state in fermionic gases near Feshbach resonances, including exact solutions for stability and dynamics.

Findings

Stable atom-molecule coexistence identified

Phase diagram of the mixed state mapped

Nonadiabatic dynamics characterized

Abstract

Degenerate Fermi gas interacting with molecules near Feshbach resonance is unstable with respect to formation of a mixed state in which atoms and molecules coexist as a coherent superposition. Theory of this state is developed using a mapping to the Dicke model, treating molecular field in the single mode approximation. The results are accurate in the strong coupling regime relevant for current experimental efforts. The exact solution of the Dicke model is exploited to study stability, phase diagram, and nonadiabatic dynamics of molecular field in the mixed state.