Phonon instability and self-organized structures in multi-layer stacks of confined dipolar Bose-Einstein condensates in optical lattices

TL;DR

This study uses three-dimensional simulations to explore how confinement affects phonon instabilities and structure formation in layered dipolar Bose-Einstein condensates within optical lattices, revealing layer-dependent stability and emergent patterns.

Contribution

It provides the first detailed analysis of phonon instability boundaries and structured ground states in realistic, confined multi-layer dipolar condensates, extending previous 2D models.

Findings

Phonon instability boundary depends on the number of layers.

Structured ground states emerge near the instability boundary.

Potential indication of roton instability onset.

Abstract

In calculations to date [1,2] of multi-layer stacks of dipolar condensates, created in one-dimensional optical lattices, the condensates have been assumed to be two-dimensional. In a real experiment, however, the condensates do not extend to infinity in the oblate direction, but have to be confined by a trap potential, too. By three-dimensional numerical simulations of this realistic experimental situation we find a crucial dependence of the phonon instability boundary on the number of layers. Moreover, near the boundary of the phonon instability, a variety of structured ground-state wave functions emerges, which may indicate the onset of a roton instability [3,4].