Superfluidity and Stabilities of a Bose-Einstein condensate with periodically modulated interatomic interaction

TL;DR

This paper theoretically investigates how periodic modulation of interatomic interactions in a Bose-Einstein condensate affects its superfluidity and stability, revealing that strong modulation leads to complete loss of superfluidity due to instabilities.

Contribution

It introduces a theoretical analysis of superfluidity and stability in a BEC with periodically modulated interactions, highlighting the impact of modulation strength on stability.

Findings

Small modulation causes instability near the Brillouin zone edge.

Strong modulation induces dynamical instability in all Bloch waves.

Periodic BEC can lose superfluidity entirely under strong modulation.

Abstract

We study theoretically the superfluidity and stability of a Bose-Einstein condensate (BEC) whose interatomic scattering length is periodically modulated with optical Feshbach resonance. Our numerical study finds that the properties of this periodic BEC are strongly influenced by the modulation strength. When the modulation strength is small, only the Bloch waves close to the Brillouin zone edge suffer both Landau and dynamical instabilities. When the modulation strength is strong enough, all Bloch waves become dynamically unstable. In other words, the periodic BEC loses its superfluidity completely.