Hybrid multi-site excitations in dipolar condensates in optical lattices

TL;DR

This paper explores how long-range dipole-dipole interactions in optical lattices cause hybridized excitations across multiple sites, leading to enhanced roton features and potential instabilities in dipolar condensates.

Contribution

It introduces the concept of hybrid multi-site excitations in dipolar condensates within optical lattices, highlighting their collective band-like nature and impact on rotonization.

Findings

Hybrid excitations form band-like structures across sites.

Dipolar interactions significantly enhance roton features.

Possible roton-instability induced by mode hybridization.

Abstract

Strong 1D lattices usually lead to unconnected two-dimensional gases. The long-range character of the dipole-dipole interactions leads to a novel scenario where non-overlapping gases at different sites may interact significantly. We show that the excitations of non-overlapping condensates in 1D optical lattices acquire a band-like character, being collectively shared by different sites. In particular, the hybridization of the modes significantly enhances the rotonization of the excitations, and may induce roton-instability. We discuss the observability of this effect in on-going experiments.