Stability and Dynamics of Atom-Molecule Superfluids Near a Narrow Feshbach Resonance

TL;DR

This paper explains the stability and dynamics of atom-molecule superfluids near a narrow Feshbach resonance, highlighting how it enables large molecular fractions and superchemistry phenomena, and opens avenues for exploring quantum criticality.

Contribution

It provides a microscopic theory showing how a narrow Feshbach resonance in $^{133}$Cs leads to stable superfluids and superchemistry, revealing new quantum phenomena.

Findings

Narrow Feshbach resonance enables large molecular superfluids.

Superchemistry is assisted by formation of bosonic Cooper-like pairs.

Potential to explore quantum critical points in molecular Bose superfluids.

Abstract

The recent observations of a stable molecular condensate emerging from a condensate of bosonic atoms and related "super-chemical" dynamics have raised an intriguing set of questions. Here we provide a microscopic understanding of this unexpected stability and dynamics in atom-molecule superfluids; we show one essential element behind these phenomena is an extremely narrow Feshbach resonance in $^{133}$Cs at 19.849G. Comparing theory and experiment we demonstrate how this narrow resonance enables the dynamical creation of a large closed-channel molecular fraction superfluid, appearing in the vicinity of unitarity. Theoretically the observed superchemistry (\textit{i.e.}, Bose enhanced reactions of atoms and molecules), is found to be assisted by the formation of Cooper-like pairs of bosonic atoms that have opposite momenta. Importantly, this narrow resonance opens the possibility to explore the quantum critical point of a molecular Bose superfluid and related phenomena which would not be possible near a more typically broad Feshbach resonance.