Static and Dynamic properties of a Fermi-gas of cooled atoms near a wide Feshbach resonance

TL;DR

This paper introduces the Global Spin Model to analyze static and dynamic behaviors of ultracold fermionic gases near broad Feshbach resonances, revealing high sensitivity of molecular production and BCS condensate formation.

Contribution

The study presents a novel theoretical framework that simplifies the molecular production process to a Landau-Zener problem, highlighting the effects of strong interactions and initial conditions.

Findings

Molecular production is highly sensitive to initial magnetic field values.

A large BCS condensate forms over a broad momentum range.

The model predicts condensate amplitude dependence on detuning and sweep rate.

Abstract

We introduce the Global Spin Model to study the static and dynamic properties of the ultracold fermionic gas near the broad Feshbach resonance. We show that the problem of molecular production, in a single-mode approximation, is reduced to the linear Landau-Zener problem for operators. The strong interaction leads to significant renormalization of the gap between adiabatic levels. In contrast to static problem the close vicinity of exact resonance does not play substantial role. Two main physical results of our theory is the high sensitivity of molecular production to the initial value of magnetic field and generation of a large BCS condensate distributed over a broad range of momenta in a wide range of parameters. We calculate the amplitude of the condensate as function of the initial detuning and the rate of the magnetic field sweep.