Roton spectroscopy in a harmonically trapped dipolar Bose-Einstein condensate

TL;DR

This paper investigates the emergence of a roton spectrum in a harmonically trapped dipolar Bose-Einstein condensate, demonstrating how it can be detected via Bragg spectroscopy and providing a validated theoretical framework.

Contribution

It introduces a local density approximation-based theory for the dynamic structure factor in dipolar BECs with roton features, validated against experimental measurements.

Findings

Roton spectrum appears in the static and dynamic structure factors.

Bragg spectroscopy can effectively measure the roton spectrum.

Theoretical model accurately predicts experimental observations.

Abstract

We study a harmonically trapped Bose-Einstein condensate with dipole-dipole interactions in a regime where a roton spectrum emerges. We show that the roton spectrum is clearly revealed in the static and dynamic structure factors which can be measured using Bragg spectroscopy. We develop and validate a theory based on the local density approximation for the dynamic structure factor.