Stability of a BEC with Higher-order Interactions near a Feshbach Resonance

TL;DR

This paper investigates the stability of a Bose-Einstein condensate near Feshbach resonances, incorporating higher-order interactions and multi-channel effects, revealing conditions for enhanced or suppressed stability and proposing experimental probes.

Contribution

It introduces a modified Gross-Pitaevskii model including higher-order terms and multi-channel effects to analyze BEC stability near Feshbach resonances, highlighting new stability regimes.

Findings

Stability can be enhanced or suppressed near Feshbach resonances.

Significant deviations in critical particle number occur at scattering length zero-crossings.

Effects are more pronounced for narrow resonances or tighter traps.

Abstract

We consider the stability of an ultracold trapped Bose-Einstein condensate near a Feshbach resonance. Using a modified Gross-Pitaevskii equation that includes higher-order terms and a multi-channel model of Feshbach resonances, we find regions where stability can be enhanced or suppressed around experimentally measured resonances. We suggest a number of ways to probe the stability diagram. Using scattering length zero-crossings huge deviations are founds for the critical particle number. Effects are enhanced for narrow resonances or tighter traps. Macroscopic tunneling of the condensate is another possible probe for higher-order interactions, however, to see this requires very narrow resonances or very small particle numbers.