Feshbach resonances in a quasi-2D atomic gas

TL;DR

This paper studies how strong confinement in a quasi-2D atomic gas affects Feshbach resonances, revealing shifts in resonance position, damping effects, and proposing a 2D model for superfluidity research.

Contribution

It provides a detailed analysis of confinement-induced shifts in Feshbach resonances and introduces a 2D model system with exact relations for experimental study.

Findings

Resonance position shifts with confinement strength

Resonance damping in thermal gases

Sharp resonance in condensates due to many-body effects

Abstract

Strongly confining an ultracold atomic gas in one direction to create a quasi-2D system alters the scattering properties of this gas. We investigate the effects of confinement on Feshbach scattering resonances and show that strong confinement results in a shift in the position of the Feshbach resonance as a function of the magnetic field. This shift, as well as the change of the width of the resonance, are computed. We find that the resonance is strongly damped in the thermal gas, but in the condensate the resonance remains sharp due to many-body effects. We introduce a 2D model system, suited for the study of resonant superfluidity, and having the same scattering properties as the tightly confined real system near a Feshbach resonance. Exact relations are derived between measurable quantities and the model parameters.